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CONDITIONS AND HABITAT OF BATS
Bats are found all over the world. There are more than two thousand different varieties, classed as the oldest of mammals, and, geologically considered, going back millions of years. As the larger species, or fruit-eating bats, are of no concern for our purpose, we shall consider only the small and beneficent species of bats which are gregarious, or live in colonies, and only resemble, but are not kindred to, the malevolent vampire bats of South America, or the fruit-eating bats of the tropics.
The bat gets its scientific name principally on account of its nocturnal habits; the zoological name of the species most common, being Nyctinomus Mexicanus, the word "nyctinomus" meaning "night mouse." In different countries they are referred to by different names, among them being "heaven mice," "sky mice" and "winged mice;" but the French have a most peculiar designation in "Bald Mouse," for certainly the bat is anything but bald, though its wings are.
There are very few, or none, of Nature's creatures that offer more anomalies and present more difficulties for study. It is distinctly a mammal, and usually brings forth one or two young annually.
To the average laymen, particularly the ladies, if the adjectives gruesome, repulsive, and repellant were added to those employed by Mr. Edgar Alien Poe in his "Raven," grim, ungainly, ghastly, gaunt, and ominous, they would just fit their ideas of the bat's personal appearance. But, notwithstanding all this, to them in particular is the bat a most valued friend.
If the ladies of any community were told that there was a natural agency existing among them that actually ruined that most desirable of charms, a beautiful complexion, and if to destroy this natural agency they were asked to raise a large fund, it goes without saying, that the said fund would be over-subscribed. Nothing is so common a cause of the destruction of a beautiful complexion as the malarial parasite which the malarial mosquito implants directly in the blood-stream, and which liberates, during its existence in the blood, a deep brown coloring matter, known as melanin. This pigment or coloring matter, which is insoluble, deposits itself under the corium or true skin; and then a dirty, yellowish, sallow shade takes the place of the school-girl complexion.
It seems that Nature in evolving the bat tried to build as nondescript a creature as she knew how, throwing in a little of this and a little of that, to see what would result; but when we study its anatomy, we see that Old Dame Nature, rearing her creatures with her illimitable and inimitable faultlessness, has made no mistakes, when she created this animal for the purpose she intended it. It is not a bird, yet it has some of the anatomy of birds. It has no feathers, yet can put many a bird to shame in flight. It is nocturnal, yet has very small eyes in contradistinction to birds and other creatures that must find their food at night.
Its normal habitats are caves, caverns, and sometimes abandoned mines or quarries; and some of these it occupies by the millions. There are, however, a great many caves in the wilderness, some of which look as much alike as two peas, yet the one will be inhabited by millions of bats, and in the other not a single bat is to be found. In other caves, a layer of very, very old guano one or two inches in depth with not a single bat in the cave, gives conclusive testimony to the fact that for a short time bats were inhabiting it, but conditions and environments to their liking were not there, so they did not remain. There are hundreds of caves that, for these very reasons, are not inhabited by bats, notwithstanding that they have been in existence "since first the flight of years began." We shall have occasion to revert to this feature of a bat cave when we reach the THIRD ALLEGATION. In the State of San Luis Potosi, Mexico, is to be found a very, very old mine, that was worked by the earliest Spaniards, and abandoned on account of the ore giving out. This old mine, several hundred feet in depth, with its many tunnels aggregating miles in length, became inhabited by these creatures; and, as it was not emptied nor worked for commercial purposes, in the course of time it became entirely filled with guano, so much so as to shut out the bats themselves.
Going into a bat cave is very much like going into an ice factory in which an ammonia pipe has burst. The extreme darkness, the ammonical gases generated in the caves by the decomposing guano, which almost robs the air of sufficient oxygen to sustain life, a pair of glistening green eyes of some wild animal, with the occasional biz-z-z-z of a rattlesnake's frightful warning, and wading in one or two feet of soft guano constitute the environment in which the student of bats finds himself; and such conditions are not in the least calculated to stimulate his enthusiasm for scientific research.
It is astonishing on what a small amount of oxygen these mammals can thrive, when we consider that they have the lung capacity for remaining on the wing in continuous flight for ten or twelve hours. They hang to the roof of the cave by the millions, touching one another, and even hanging on one another in huge bunches which resemble swarms of bees; and how those in the center of these bunches keep from suffocating is simply inexplicable.
There is no cave inhabited by bats, whether worked for commercial purposes or not, that in some remote time had not been on fire, as evidenced by the entire floor being covered by compacted ashes, sometimes fifteen feet thick. This occurs only in caves that are not worked, and in which the guano is allowed to accumulate, and into which rain finds its way. The fires are brought about by chemical combustion from the heat generated by the decomposing guano, which is eventually largely converted into nitrates and nitrites, or saltpeter. A cave on fire in the mountains at night is indeed a rare sight, as the reflection coming from that seething furnace is no larger than the opening, which is sometimes but a few feet in diameter. If the opening is on the side of the mountain, the darkness all around it, the intense stillness and solitude, with the tips of a few trees silhouetted, give it the weird appearance of a cyclopean eye. The bat caves on fire are referred to by ranchmen in the vicinities as "smoke holes." As it is these caves that furnish the bats with the conditions and environments to their liking, they return to them when the fire dies out and the cave has cooled off, which sometimes takes many months.
REGULAR HABITS AND MOVEMENTS OF BAT COLONIES
Besides the most wonderful instinct of orientation that bats have, and which will be described later on, they possess also to an eminent degree that of migration. It is this instinct of migration that we can take advantage of and cause to render us its great hygienic and economic benefits. Observations in the well-tenanted caves verify this instinct, as millions of bats leave the caves with the coming of spring and summer, and return with the advent of autumn and winter. This is well known to people who own bat caves and work them for commercial purposes. Several years ago, and again last year, it was the good fortune of the author to see a swarm of bats at least one mile wide and six miles long, travelling in a northeasterly direction. A prominent fisherman on the east coast of Florida related to the author how he had often seen bats flying over the Florida Keys in such numbers as to throw a cloud or shadow on the water. He has a fleet of fishing boats, and both he and his men have seen them flying all day long in one huge mass. They were migrating from the south, going north, seeking their food.
NORMAL POSITION FOR REPOSE
The normal position of bats in repose is hanging head downward by their short hind feet, which resemble tiny hands and are provided with very sharp-pointed, curved, rigid claws. These it can spread out, but the angle of curvature remains, so that when it hangs, no muscles are brought into action, hence volition plays no part; and their claws, once finding a place to hook to, insure perfect hanging with all free body movements, such as scratching itself, love-making, etc. Often it will loosen its hold of one foot and employ it in scratching the back of its neck to rid it of some troublesome parasite, while hanging on with the other foot.
After death bats are still found in the hanging position. An idea of the fineness of their claws can be had when we examine an ordinary piece of rough 2x4 inch lumber rendered as smooth as if sand-papered by hand, on which these little mammals had been roosting for a number of years. When crawling along on a horizontal surface, they depend more on the hook-like apparatus at the thumb joint on their wings for propulsion than on the hind legs, though these assist somewhat, but in a very awkward way, being spread out in a manner similar to that of the toes on a horned-toad's hind legs.
On flying to their perches where they roost, in old barns and abandoned houses, during the feeding season, they sometimes make several unsuccessful attempts to land in their roosting places, one attempt following the other; this is due to their failure in securing the preliminary hold with the flexible hook at the thumb; but once off the wing, they immediately bring their hanging position into use.
The ungainly, froglike angle of their hind legs fulfills two distinct purposes. As the legs are inserted in the folds of its web, this brings that portion of the flying apparatus in control of the legs, permitting them to act as a rudder that can be extended or contracted at will. When the bat is in repose, one can readily see how perfectly the legs are situated in relation to the centre of gravity.
THE BAT'S SUPER-ACUTE SENSES
As far as the author has been able to ascertain, the bat is the only animal that hunts its food through the sense of hearing, although it will follow a large moth around an electric light for a few seconds, as if employing both sight and smell, before devouring it. A great many nocturnal insects are provided by Nature with acrid or even blistering fluids for their protection, and how the bat in its rapid flight avoids these insects is, the writer believes, accounted for by the fact that it will attack only such insects as emit certain tones in their flight; and it is through the tones so made by the vibrations of the insect's wings that the bat distinguishes the species best suited for its food. As a result of many observations along these lines, the author has found that insects emitting a tone lower than C natural, first ledger line below the staff (International pitch 440), are avoided by bats. The tones emitted by mosquitoes range from staff D, to F, G, and even higher.
The afore-mentioned observations were made under an electric arc-light around which hovered innumerable insects attracted by the glare, as well as a number of bats attracted by the presence of the smaller winged creatures. With an insect net the author caught a number of these insects which, it had been previously observed, the bats were rejecting; also a large number of mosquitoes and other insects of the species which the bats were devouring.
In the case of the rejected insects, on causing them to fly in the net the tones emitted were invariably lower than C natural; while for the accepted insects, which, by a large per cent, were mosquitoes, the tone ranged from C sharp (staff) to F or G. The sudden dips, dashes, and dives the bat makes through space also support this observation; for these quick dashes, due to objects entirely out of its range of vision, could only be induced by its hearing some favorite insect in that locality.
Another convincing proof of this assertion, and one which is in entire accordance with the foregoing, is that the flight of the bat is noiseless. The accompanying enlarged photograph of a bat's ear shows the anatomy of that organ to correspond with our knowledge of the physics of sound; because the cartilaginous concentric ridges correspond to the spherical soundwaves, while the cartilaginous, conical projections placed on the edge of the ear are to break these sound waves, should they pass above the said cartilaginous ridges.
THE BAT'S HAIR
The hair covering any animal's body serves it as a protection against the vicissitudes of the different seasons, as is evidenced by the fact that it sheds the light coats of Spring and Summer, and acquires a dense and heavy coat during the Autumn and Winter. Hair is generally cylindrical in cross-section ; usually it is straight, and although it might be curved or even curly, it will still retain its round shape. Again, it might be either highly or lightly colored, but still retaining the characteristics peculiar to the animal it covers.
With the bat's hair it is entirely different, as will be seen in the picture marked "Bat's Hair Highly Magnified." There we see three different and distinct sorts of hair, and a radical departure from the form of the ordinary kind. This peculiar hair covers its entire body, and is not confined to any particular or selected place. All through the aeons of time the hair covering a bat's body has undergone no change. Unlike most mammals, the bat does not shed its hair, as Nature has converted its body into a vital radio, the hairs serving in a most admirable manner as antennae for capturing the different sound waves emitted by mosquitoes and other small insects in their flight, thereby enabling the bat to catch them.
Ordinarily-round wire serves the artificial radio quite well, but in the bat's hairs we see the construction of natural antennae intended to capture sound waves, and we also see three different kinds of construction which ordinary reasoning tells us is for capturing sound waves of different characteristics, regardless of the number of vibrations per second of time. All of this peculiar and extraordinary hair-formation, in addition to the wonderful anatomy of the bat's ear, is destined by Nature for the procurement of the animal's food; and as it was that infallible Old Dame who made sound waves, surely no one more competent than she could have constructed a food-procuring device to serve in the perpetuation of a species to endure through unknown millions of years.
But this most remarkable and peculiar hair not only serves the bat as a means of procuring its food, but it also protects the animal against its natural and principal food, the malarial mosquito. It is a well known fact that the female mosquito cannot oviposit, or better said, her eggs will not ripen in her body without albuminous or animal food; and, in obedience to the inexorable laws of Nature, this insect might possibly transmit to the animal the diseases she sometimes carries. As matters stand, it is the dense hair with its innumerable lances and pockets which prevent the mosquito's proboscis from reaching the bat's skin.
TESTING BATS' HEARING
That Nature always gives a creature protection from its enemies in some form or another is a matter of common knowledge. Accordingly, if the bat is the arch enemy of the mosquito, surely this insect must have some method of protecting itself against that creature. Just what form of protection the mosquito resorts to is readily reasoned out; the mosquito must stop its flight to protect itself, for it is by the vibrations of its wings that the characteristic sound waves are produced, attracting the bat's attention. In order to prove this line of thought, the author made an experiment which places this point out of theory and into fact.
A small room, 10 feet long, 5 feet wide, and 5½ feet high, was thoroughly cleaned, canvassed, and white-washed. The room had one small window to the east and a door to the west, both of which were thoroughly screened with fine wire mesh. Tens of thousands of mosquito eggs were procured and placed in a tub of cistern water, to which there was previously added some organic matter to furnish food for the larvae. In the course of time thousands of mosquitoes hatched out. and these were fed by placing two turkeys and two old fat hens in the room until all the mosquitoes were hatched.
At night, after the mosquitoes had developed into adult insects, their buzzing noise could be plainly heard several feet from the room. On one occasion the writer entered the room with a darkened electric flash light and liberated two bats. Instantly the buzzing noise ceased, and on turning on the light it was observed that the mosquitoes were clinging to the walls and perfectly motionless. On taking the bats out of the room, in less than three minutes the buzzing noise was resumed. This experiment was afterwards repeated several times with the same results.
Some few days after making the above experiment, the author had occasion to go to the Mitchell's Lake lands, as he had done every Friday for years, devoting that day of the week, during the spring and summer, to the exclusive study of bats. He was met by one of the lowly peasants who was a great admirer of the bat roost and the study that was being conducted on those lands. He asked the author if he recognized that the mosquitoes actually know how to defend themselves from the bats. After receiving a rather evasive answer, made with the object of drawing from him what might prove a valuable observation, or at least, perhaps, a clue to the habits of bats and mosquitoes that study might develop, he said he had watched mosquitoes and bats in his cabin for a few nights, on account of the interest he took in them, particularly in the destruction of the insects, and because of his desire to aid in the work. His own words tell the story best: "I have been noticing," said he, "how funny it was the buzzing noise of the thousands of mosquitoes in my cabin at night stopped * instantly when the bats came in. Oh, I tell you the mosquitoes are sure smart. One night, the mosquitoes were so bad, (i. e., there were so many of them), that their singing noise was loud enough to bother my sleep. Of course I sleep under a mosquito bar, but wanting to watch these things for you, I had a good chance on account of the moon shining so bright; and in my house I could see the mosquitoes very plainly, so kept awake. The funny sing-song of the mosquitoes was one and the same tune, until a gang of bats came into the cabin. Right away the tune shut off, all you could hear was the bats' wings hitting against one another, and another little noise of which I don't know the causebut it was no mosquito tune. When I saw the bats leave I got up out of my bed and lighted my lamp. There they were, hidden from the bats, and plenty of them right under my bed. Ain 't mosquitoes smart?''
The "noise" of which our peasant friend "did not know the cause" was produced by the rapidly-moving jaws of the bats in the characteristic munching of their prey. When they dive into a swarm of mosquitoes, this can easily be heard, as they must catch the insects with astounding rapidity, before the latter adopt the defense of closing their wings and dropping to the ground, grass, or wherever they may be. It is a very singular sight to see a swarm of mosquitoes so thick as to resemble a black mass of smoke suddenly vanish on the appearance of the bats.
It is a very common experience to see a bat enter a dwelling well lighted, and fly about the room, over, under, and between the most delicate of bric-a-brac, without as much as touching any of it. It did not enter seeking a home, as it never intended to remain, nor did it want any food belonging to the home owners, or even to do them the least harm imaginable. It entered seeking its own food; and, if left alone and unmolested, it will always leave as suddenly as it came, and with it, or better said, inside of it, will go all of the mosquitoes that were in the room. However, this rarely happens, as the entrance of a bat into a room or dwellings brings about consternation ; and every occupant will seek the nearest umbrella, broom, or what not, to swat the little sanitary messenger who entered on its beneficent mission, only to be rewarded with pain and death, and that at the hands of the highest of beings, to whom he is such a friend.
Nature having so admirably protected the bat from the bite of the mosquito, she carries her protection to greater depths by adapting one of its internal organs to the character of the food she intended for its nutrition. It is from this internal organ that we get some startling and affirmative information which constitutes one of the strongest points in the demonstration of the fact that the malarial mosquito is the natural and principal food of the bat. However, a little serious reflection would lead us to think, and rightfully conclude, that when Nature intended the blood in the mosquito's body to be vitiated by one of her own creatures so as to become wholesome food for the bat, she also made some provision for that vitiated blood to become wholesome for that creature, just as she provided for the putrid flesh of a dead animal to become wholesome food for a buzzard. The internal organ referred to is its spleen, a detailed study of which will be found hereinafter under the head of "FUNCTIONS OF THE SPLEEN."
THE BAT AN INTELLIGENT HUNTER
The author had a friend who, becoming deeply interested in the bat as a destroyer of mosquitoes, paid him periodical visits with the object of enquiring as to new experiments or developments in the bat work. He became quite an enthusiast, ever pleading with the author to continue the work, and offering words of the highest praise as encouragement,
One morning he came to the author's office, his face beaming with radiant smiles, and said: " I have something that to the average man would mean but little, but knowing you as I do, to you it is the grandest treat of your life." It really proved a treat of the highest order. He occupied a room on the third floor of a hotel in the central business district; and it happened that this building was not provided with wire screens. Across the street from his room is a large department store. One morning he awakened about five o'clock; and, in thinking about his business affairs, his sleep left him, then he turned his face toward the open window, gazing aimlessly into the empyrean. It was not long before he saw the ''treat,'' in fact, quite a number of them, which aroused such enthusiasm in him that he forget not only his sleep but his business affairs as well.
The next morning at 4.30 o'clock the author found himself with his friend in the latter's room sitting on the carpet before the open window, looking at the gradually approaching dawn. It was not long before a bat flew by, then another and another. On looking out of the window, the author counted the bats, to make the observation more correct. There were just four bats flying backwards and forwards on the hotel side of the street. Presently we saw an engorged mosquito flying slowly out of the window, being burdened with an abdomen full of blood. It had not gone three feet from the wall, when a bat got it in plain sight of both of us. "Ain't that great? That's the treat," shouted the friend, adding emphasis to his enthusiasm with a hard slap on the back, and some more words of encouragement.
But the author was almost without feeling or hearing, even speechless, not at the sight of one engorged mosquito being waylaid by the bats, but at seeing every one that left the room captured with the most dextrous facility and unerring certainty. Not a single mosquito escaped our eager eyes, neither did it escape the keen ears of the noiselessly-flying, acrobatic sentinels on the outside of the room. Sometimes the bat in its flight would be as much as two feet above the flying mosquito, but on approaching it and getting the sound of its wings, would instantly arrest its flight, turning what appeared to be a complete somersault, but righting itself almost in the same instant. When flying below the emerging mosquito, it seemed to have the facility of gyrating upwards, the movement being executed with incredible rapidity; again, it appeared to approach the mosquito at an angle, as if volplaning. However, whether gyrating, somersaulting, volplaning, or whatsoever manner of flight or complex aerial movements the bat employed, the fact remains that it got the mosquitoes, and we SAW it in the act of catching them.
The reader can well imagine the emotions aroused in the author at this sight, and the frenzied ecstasy of witnessing with the eye the creature he had so intensely and laboriously studied in his endeavors to find the evidence he believed would entitle it to an exalted place in the domain of hygiene, exhibiting its true nobility and making its own evidenceand that evidence of such an uncontradictory character as will permit it to pass through the molecular meshes of scientific scrutiny.
As the mentioned screenless hotel is only one block from the author's office, it made observations of the bats there very convenient indeed. At no time, whether in the spring, summer, or late fall, were the bats ever observed parading in front of the hotel windows in the evening. They were to be seen only in the very early morning, and at no time in front of the windows of the large department store across the narrow street. The reason is quite patent; on that side of the street there was no food, neither was there any food on the hotel side until early in the morning, when the engorged female mosquitoes left the room to seek the male and water.
NATURE'S PHYSICAL ECONOMICS
Bats are conserved by going into a state of suspended animation, or hibernation, in the place where they roost for the winter. They can be heard screeching and moving about on warm days; but after a cold snap they can be handled like so many dead sparrows, tossed and thrown about, apparently lifeless. A rare heartbeat can be distinguished, but no diaphragmatic breathing; and their bodies are as cold as the surrounding temperature. A temperature of 25 degrees below zero does not seem to disturb them at all; for they are found in Vermont in caves where the temperature falls that low in the winter months. When caught in the winter and placed in a warm room they soon revive and fly aboutjust as in midsummer. Nature has so beautifully balanced their winter rations that flying about in a warm room calls for energy, and that energy for food, so that they consume the food intended to tide them over the winter, and consequently die within a day or two.
This has been the oft-repeated experience of the author in handling and studying bats in the winter time; but, as everything about a bat seems to be reversed, they can be observed exercising in mid-winter after a little warm spell. In several buildings where bats find lodgment, they can be seen flying backwards and forwards on the outside at a great velocity, but for only a few minutes. This would lead one to conclude that they have the remarkable property of drawing on their fat for food at will. The rapid flying could be nothing other than exercise, as in mid-winter in this climate there are no mosquitoes or other insects they might be seeking.
They accumulate quite an amount of thoracic and abdominal fat, as was evidenced by post-mortem examinations made during the month of November. The average weight of the free-tail bat about the middle of February, when its period of hibernation is at an end, is about two drachms and five grains, or a trifle more than one-quarter of an ounce; and towards the middle of the month of November, when its feeding season is about to close, its weight is about three drachms and forty grains, or nearly one-half ounce. They are particularly active after the month of July, as it is from then until the feeding season closes that they must accumulate the necessary fat to tide them over the winter months, when there are no mosquitoes.
A number of bats with their wings against their bodies were wound around and around with a string that gave them the appearance of little bobbins of cotton yarn; these were fastened to a long string by their legs and then whirled horizontally at great velocity for some time, the object being that the centrifugal force, by driving an excess of blood to the brain, might blunt that organ, and deprive them of the natural endowment of orientation. Another number of bats were fastened in like manner, but the position reversed, viz., fastened by the necks, and whirled around and around, to drive the blood from the brain. These severe ordeals had not one iota of effect on them, as, when liberated, they all behaved alike, quickly ascending quite high, and, after making a short circle, flying directly for home.
When bats are placed in a box the sides of which are covered with ¼-inch wire mesh, they soon huddle in some corner, hang in one or two bunches, and become perfectly calm. It is then that their heart's action and respiration can be so beautifully observed; the said heart's action slows down, and the rate of respiration is diminished by the contracting of the lungs. As it is normally at rest in a cave where the oxygenis almost replaced by the ammoniacal gases, the lungs contract to present less pulmonary area to the vitiated atmosphere.
Unlike a wild bird, the bat makes no frantic efforts to escape; and, in observing a single specimen, it can be handled with the greatest of ease, if we but allow it to get a hold with its claws or feet. As long as its claws find nothing to hold to, it is very restless ana will bite and endeavor to escape. Its heart beat and respiration are then very fast, and it is ready for flight; but as soon as it finds something to fasten its claws to, both of these functions begin immediately to diminish. If after a little time we place it in the palm of the hand, it begins to turn its head from one side to the other in a very awkward manner as if to survey as long a range as possible; then its heart begins to run away, and its lungs to expand, when it will extend its wings, because its "motor" has acquired the requisite speed, and only needs to be thrown into action, to enable it to fly away.
If, after being kept in a screened box and not molested for a considerable time, a small aperture is made for the bats' escape, this can be beautifully observed, as, in the act of escaping, each bat rests on the outside of the box for a few seconds waiting for its "motor" to generate speed. If, however, we disturb them by vigorously shaking the box, and then allow them to escape, this lingering and awkward surveying at the aperture on the outside of the box does not occur, because they have prepared themselves for flight.
HARMLESSNESS OF BATS
About the only harm the writer ever has known a bat to do is that it will get into smokehouses and eat the fat from hams and bacon. If it can find a piece of bacon with the "streak of fat and streak of lean," it will eat the fat as far as its mouth will permit, and avoid the lean meat. Here it finds the necessary fat, therefore its struggle for existence for that year is over.
The facility with which a bat can compress itself into a small opening is a provision for protection against one of its most formidable enemies, chicken snakes. A bat can get into any long opening of the width of an ordinary lead pencil. The important parts of its anatomy are arranged by Nature for this facility. The author, some years ago, in observing bats in an old barn, killed a chicken snake that had swallowed fourteen bats.
The author desires very much to correct a popular impression which is a most unjust accusation against these valuable creatures; and that is that they carry bedbugs. As stated before, the long distances from their caves to suitable feeding grounds cause the bats to seek any dark hiding place, and they will sometimes get behind the loosened bark of a dead cottonwood tree, where is found in huge numbers in the immature stages an insect entirely distinct from the familiar human bedbug (Cimex lectularius). It is then that these larvae mechanically cling to the bats and are carried about by them until they either drop off or mature into the adult insect. The larvae, so closely resembling the true bedbug, are not such, as that insect does not thrive on dead cottonwood trees. The author begs to quote thus from Circular No. 47, United States Department of Agriculture, Bureau of Entomology, by C. L. Marlitt, page 4: "There is a prevalent belief among the old settlers in the West that the insect (bedbug) normally lives on dead or diseased cottonwood logs, and is almost certain to be abundant in log houses of this wood. This belief was recently voiced by Captain S. M. Swigert, U. S. A., who reported that it often occurs in numbers under the bark of dead trees of cottonwood (Populus Montilfera), especially along the Big Horn and the Little Horn Rivers in Montana.
"The origin of this misconceptionfor such it is, so far as the out-of-door occurrence is concernedis probably due, as pointed out by Professor Riley, to a confusion of the bedbug with the immature stages of an entirely distinct insect (Ardus sp), which somewhat resembles the former, and which is often found under dead cottonwood bark.''
During the many years the author has been studying these creatures, he has never found a single bedbug on a bat. Some years ago he kept track of the number of bats he very carefully examined for bedbugs; and it amounted to more than four thousand. In bat caves, with millions of bats, there are no bedbugs to be found. In the bat roost at Mitchell's Lake in which are housed hundreds of thousands of bats, there has never been found a single bedbug. Bats are infested with a small louse, that looks something like a chicken mite, and also with a very beautiful specimen of "bird tick." These latter specimens of different species are found on doves, quail, and pigeons. The little louse on the bat will not remain on the human, as the writer knows from exposing his own person for a long time in a bat cave inhabited by millions of bats, for the express purpose of gaining this knowledge.
Bats seeking a resting place in the daytime during the migration period, will sometimes find such a place in dwellings, and usually under the roof; of course, they are very undesirable, though they have not gnawed their way in like a rat or mouse, but have found entrance through some defect in the workmanship, or perhaps because of a sinking of the building that leaves an opening for them to enter.
The flight of bats, from the beginning of the feeding season to about the end of July, is very erratic; sometimes the flight begins as early as 6:30 o'clock p. m., and sometimes as late as 1 and 2 a. m.; and very often only about half of them leave their roosting places to forage. However, from the first week in August until the end of the season, they all fly out quite early, though some might be later than others. This is the most appropriate time for getting rid of them without injuring or killing them, in a very effective manner, which consists of simply closing the openings from which they are seen to emerge. It is perhaps well to observe out of how many openings they are emerging, and close all of them but one for some days before shutting the last opening; and, when this is done, it should be quite late in the evening, in order to insure all of the colony having left. In the morning after the opening has been closed the bats will return and attempt to re-enter by flying up to the closed place to get the preliminary hold with the little nail or claw on the top of their wings. Failing to find lodgment, they will leave, and will be gone as much as an hour, only to return and again make several attempts to find their resting place. After several such repeated attempts they will leave for good; and the dwelling will be rid of them, for they will have found themselves a new home.
There is no winged creature that has such an amazing muscular strength to furnish it wing power. For instance, a bird will begin its search of food with the advent of day, but is on the ground, or perched on some limb, or sitting at rest at least two-thirds of the time. A buzzard or vulture will rise to a certain level by the flapping of its large wings, which in a most mysterious manner serve as a motorless airplane and enable the bird to soar for hours, without the expenditure of any considerable muscular energy.
Sometime ago the author had occasion to make a sea trip from Havana, Cuba, to New Orleans, La.; and his most interesting experience on that forty-eight-hour voyage was to watch the sea-gulls in quest of food. The skipper referred to them as "his old friends crossing the Gulf with him." They seemed to know almost the exact time when the table scraps and kitchen refuse were to be disposed of by dumping overboard, as they would then appear and follow the ship for miles.
When tired, they rested on the water and remained there for several hours, appearing again for quite some distance behind the ship, which they would gradually catch up with and continue their hunt for food. Their large wings, designed for rapid flight and soaring, with the surface of the water available for complete support, enable them to rest at least half of the time in the long journey of seven hundred miles across the Gulf of Mexico.
But our little friend, the bat, with comparatively short wings which it keeps continually flapping from 250 to 300 times per minute for 10 or 12 hours, and sometimes longer, with the additional calls for energy in making all kinds of dips, dives, and dashes through space in its quest of food, does not rest for one single moment from the time it leaves the roost towards evening, until it returns from its sanitary mission, back to the roost in the morning. The roost referred to here is what the author calls his '' Mitchell 's Lake Bat Roost,'' a cut and description of which will follow later.
About one hour before emerging from the roost in the evening, the bats begin a small chatter, which gradually grows more animated, each individual seeming to take part in the conversation or argument and desiring to be heard. As the author has never even attempted to master the bat language, he will leave it to the conjectures of the reader as to what all the argument is about. But it is quite noticeable that some voices are louder than others and are heard more often; perhaps these voices are those of wisdom and come from the chiefs or elders who are advising or mapping out the route soon to be taken to furnish them with their daily bread.
BATS EMERGING FROM ROOST
They first come out in singles, then in pairs, then fours, tens, hundreds, after which the procession becomes one black stream, and continues so for hours, usually breaking up into three columns and going in as many different directions, flying horizontally, each fellow hustling for himself. Their return in the morning is most interesting, and is well worth the inconvenience of having to get up early and travel ten miles out in the country to see.
They do not return as they fly out, horizontally, except some few who may be feeding in the immediate vicinity, neither do they return in pairs, tens, or hundreds, but ALL return at the same time from a high altitude and drop down when over the roost, around which they circle, so as to form a great black mass seventy-five feet in diameter. This huge mass keeps circling and circling the roost, and as those nearest the structure keep on entering, the bunch gradually gets smaller and smaller until they are all in.
Imagine all the guests in a great hotel to come home at once and to enter at the same time! What a crowded scramble that would occasion! The aisles and corridors would become congested, with the corresponding confusion and bedlam that would follow. Pa would be looking for and anxious about mother, and she in turn would be looking for and anxious about William, Henry, and sisters Lucille and Corrine. This is about what happens in a bat roost, when all the guests of such an institution return in the early morning hours. There is a great scramble inside the "Hotel de Bat," which has all the conveniences any little bat heart might desire. The more timid dart about in the flying space or corridor of the ''hotel,'' awaiting room to be made by the more aggressive ones. All keep up one continuous chatter, which apparently has a different timbre from the evening chatter, due to a radical change in the theme, as now to them the hour of rest approaches, and the noise gradually diminishes as "Morpheus, the humble god that dwells in cottages and smoky cells," also dwells in their man-made home, the Bat Roost.
The high altitude the bat resorts to on returning in the morning to its roost or cave serves it in the remarkable purpose of not only finding its home, but finding it in safety. This return of the bats is indeed a marvellous sight! They are sometimes so high as to be entirely out of the range of vision, but when over the cave or Roost they drop down with frightful velocity; they close their wings, permitting gravity to accelerate the velocity of descent; and, when near the mouth of the cave, they gradually open their wings, to begin arresting their flight, and come down in a zigzag manner, something on the order of a tin disk sinking in water, then dart into the cave.
On coming out of some caves towards evening bats fly from the dark and innermost recesses to a few feet outside of the mouth of the cave which they again enter for a short distance, fly out again, and re-enter, describing one continuous circle for a few seconds, before leaving their cave on their evening pilgrimage. They come out of the cave in such huge numbers that a stone carelessly tossed across the mouth of the cave is certain to strike one or two of these creatures. The current, or circulating air, they produce in flying in and out of the cave feels to one on the ground underneath them, like the blast under a four-bladed electric ceiling-fan going at a good rate of speed.
The circling and re-entering are caused by the fact that the ammoniacal gases continuously generated in the cave irritate their eyes so that they are kept closed, and the circling and re-entering at the mouth of the cave in the presence of daylight go on, until their eyes accommodate themselves to the light. This is truly a sight worth seeing, as for hours they emerge in one unceasing stream in their noiseless flight. Nothing breaks the stillness save the soft and muffled sound produced by the accidental touching of one another's velvety wings. The spectator feels awe and reverence for Nature, for here he sees the Old Lady in her pristine glory. We marvel as we peer into the darkness of the cave, and all latent superstition, recollections of fantastic dreams, and stories of the elves of darkness and gnomes in haunted houses told us in childhood are brought up from the subconscious mind in one bewilderment of thought.
A clapping of the hands at the mouth of the cave will cause an immediate arrest of the flight, and it will be a few moments before it is again resumed. A revolver fired at the mouth will keep them in for quite some time. This indicates the timidity of the creature. Towards the end of November, on a cold night, they fly out in the circling manner described in search of food, but soon return, and for hours as many can be seen going out as are returning. This is due to the fact that the heat caused by the decomposing guano gives them no inkling as to the status of the weather on the outside.
The flying out and re-entering of bats as observed at a cave, are not seen in a bat roost, as here there are not the irritating, pent-up, ammoniacal gases to contend with, because in the construction of their man-made home, the escape of these gases is provided for. This is accomplished without in the least changing other features, which are copied from Nature, and consequently so admirably meet with the bats' approval, as we shall see later on.
HOW BATS EVADE THEIR ENEMIES
If the individual who, in order to express his ideas of velocity coined the familiar slang phrase, ''Like a bat out of Hell,'' should ever see a colony of bats returning home in the morning, he would substitute the words "cave" or "roost" for the word "Hell."
This natural manoeuvre is an admirable defense against one of their most formidable enemies, the chicken hawk. These birds of prey begin gathering in the near vicinity of a cave towards evening in anticipation of the bats emerging; and as the latter come out in such enormous numbers and fly horizontally, the hawks with the greatest of ease swoop down into the clouds of our little flying friends, and emerge with one, or sometimes two, one in each talon. Their suppers are assured, confirming the old Latin proverb, "Omnia sine labore," for they actually labor not in procuring their supper. Hawks are not to be seen in the vicinity of bat caves in the morning, as only too well do they know that they cannot match the velocity of flight the bat exhibits in returning home.
Some years ago the author spent many days, particularly the holidays in the spring and summer, at a bat cave a few miles from his home, studying these creatures, and was often accompanied on these excursions by several convivial friends who were much interested in the bat work; in fact, they were great ''batophiles,'' wanting an outing and an opportunity to try their marksmanship in such a worthy cause as killing those big, strong birds, the hawks, that came there to devour our defenseless little friends.
Of course, liquid and solid refreshments were liberally provided for the picnics, and, as an incentive to do good work, a competitive pact was agreed upon, whereby the poorest marksman, or the friend who got the least number of hawks that evening, was to suffer the infliction of a fine, this punishment being no less than payment for the said refreshments. It is needless to say that the little picnics at the bat cave saved the lives of thousands of these beneficent little creatures.
MITCHELL'S LAKE BAT ROOST
At the Mitchell's Lake Bat Roost, the author and his friends have dispatched quite a number of hawks that made their appearance at the Roost just about the time the bats emerged. But there the bats are not so easy of capture as they are not as plentiful; and we applaud, when a big hawk, swooping down in the very act of capturing one of our inoffensive little friends, is frustrated by a clever and well-directed aerial dip, and the useful little life is spared to continue its activities in the service of mankind.
It is interesting to watch the small sparrow-hawk who comes to the crowded city in search of these creatures. This diminutive falconized bird, that preys on sparrows or other small birds, will perch on the ball of a flag-staff in the vicinity of places where bats are to be found, usually under some cornice, roosting during the day.
It also, like its big brother the hen-hawk, knows when it is time for the bats to emerge for their evening flight, and is seen on the flag-pole only toward evening. As the bats emerge, it swoops down among them with wings partially closed to add velocity to its descent; but it makes very many fruitless dives, as the bat is such a wonderful aerial dodger that he side-steps his enemy, and before the sparrow-hawk can arrest its flight, the bat is safely on its way to the feeding grounds. When the bird does capture one, it proceeds right then and there to enjoy its meal. However, it is not long before some one gazing out of an office window sees him at his nefarious work, and as the bat has so many good friends in San Antonio, the murderer's career is soon ended with a silent 22-calibre bullet.
A very large barn-owl got in the habit of coming to the Mitchell's Lake Bat Roost just about dark for an easy supper. Of course the slow-flying owl is no match for the bat, but it got its supper, or perhaps its breakfast, with comparatively no exertion. It would appear about dark and flutter within a foot of the uppermost slat in the louvre, and, as the bats literally pour out of the roost at this time, some of them would actually collide with it, and of course get caught. It is needless to say that that particular owl does not make any more evening visits to the Mitchell 's Lake Bat Roost.
UPWARD FLIGHT OF BATS
If a number of bats are caught, transported for some distance, and liberated, they fly upward like wild ducks when shot at, and ascend so high as to become invisible. This is another protection from their arch enemy, the hawk. If the bat has a friend in the animal world, we have never made his acquaintance. At one time the author was transporting quite a number of bats in an empty flour barrel and one happened to escape. A large butterfly near by spied it and immediately gave chase, ascending higher and higher in close pursuit until both became invisible. The author wondered, like Mark Twain, when a small dog ran after an express train he was riding on, "What the dog would do with the train if he caught it."
BATS' WONDERFUL SENSE OF DIRECTION
In one of the preceding paragraphs it was said that the altitude in which a bat flies enables it "not only to find its home, but to find it in safety." We have seen with what admirable safety it reaches home, but not how it finds it. If, from some eminence with a good field glass, we observe a huge colony of bats emerging from a cave, they can be seen flying for miles. When they come to the crowded city and fly along the waterways, through broad streets, between high buildings, narrow alleys, and back yards, through mazes of telephone, telegraph, and electric wires, even entering our homes and churches in quest of food, we wonder how they can find their way back home. Won't they get lost traveling in the two extremes, wilderness and civilization 1 It would be impossible for them to become familiar with the region of their home, as their very small eyes afford them no long range of vision.
Unlike the human aviator, they have no object like a railroad track to guide them, or a compass set with mathematical accuracy to follow, neither are they equipped with a set of wireless instruments to direct them through the great empyrean; yet, with the unfailing accuracy of the compass, do they find their home and rest after a whole night of unceasing flight spent in the interest of humanity. Old Dame Nature has given them a faculty that serves them with the greatest ease, in that veering winds do not disturb the direction of their flight, when once the direction has been chosen.
This remarkable faculty is the wonderful power of orientation they possess. They know the exact direction of their home, whether a cave or a bat roost, and are guided accordingly. It is then that the sense of smell is brought into play, as when they find themselves over the cave or roost, no matter at what altitude, they detect the odor of the ammoniacal gases, which tells them that home has been reached, and then they drop down as described, following the odor. It sometimes happens that they drop down not straight to the cave, but at a decidedly acute angle. This is due entirely to the wind and to their direction.
The author some years ago in studying the habits of these creatures, camped near a bat cave and procured some spoilt hay. Early in the morning, in order to get the proper direction of the wind, he caused a smoldering fire to be built of the hay, and kept it smoldering to generate a large amount of smoke. The ascending smoke gave the exact direction of the wind, which, of course, carried the ammoniacal gases with it from the cave, and out of direct upward ascendency as it was wont to do, the gases being much lighter than atmospheric air. For several days the wind blew from southeast to northwest, and the bats were seen to be dropping from the northwest, after getting the odor. It also fortunately happened one morning that the wind changed from south to north, so did the descent of the bats change, as they began dropping from quite a distance from the mouth of the cave at an acute angle, and from the south, the wind blowing the odor from that direction.
Further to verify the observations of the remarkable faculty of orientation possessed by bats, one August morning the author with a large bag made of mosquito netting, caught, to be exact 2,004 of these creatures from a very peculiar cave, the surroundings of which furnished splendid environment for study. The cave is on the summit of a low, bald hill, and one of its mouths is a perfectly reamed hole in the solid rock, looking like a huge doodle-bug's home, the wide end being about 12 feet in diameter, the smaller end, or neck, about a foot and a half, and the depth about 10 feet. Out of this large rock funnel the bats emerge toward evening, but return through an entrance on the south side of the hill. Underneath this huge funnel is the beginning of the cave proper, which describes a semi-circle, and then merges into a beautiful, perfectly-straight corridor several feet in width, lined with limestone columns set as if by hand, five feet apart, and eight or ten feet high.
This is the hall and bower of a large colony of these valuable sanitarians, which the author so rudely invaded and pillaged on an experimental excursion. In a high-powered automobile the bats were taken to an open field about 30 miles from their home. Here the author liberated one bat, and watched its behavior. It took immediately to the air in the accustomed manner, and after describing only one small circle, with a velocity of flight that left no doubt as to its certainty of purpose, and made for the direction of its home. Four were then liberated; and, without the least confusion or separation from one another, in a very short time they got the proper direction and passed out of sight at a speed which would place a carrier pigeon in the pelican class.
But what of our screened box which we left in the open field with hundreds of our imprisoned little friends which we so rudely disturbed and carried away from their home and manor, thirty miles away? What might not be their heartaches, fears, and anxieties? Surely they must yearn for their loved ones, home, and rest, for were they not in peaceful repose, in one another's bosoms, richly earning a most deserved rest after a whole night's warfare in the interest of the family of that highest of beings, of which the arch disturber is a member?
Let us return to them, and give them our heartiest thanks for the noble role that their little lives play in giving us health and happiness, and restore to them that which Nature intended should be theirs, FREEDOM. Yes, we can, and will, do all this, but why not help these little dumb friends of ours to tell us more about themselves? It will lead to making friends for them when we tell of the great virtues possessed by these little mammals, who, emerging from their dim and cloistered domicile into the darkness of night, work valiantly in our behalf. They are equipped with faculties and endowments for destroying that fiend of the insect world, the mosquito, who carries a pocket of little living things and a hypodermic needle, ready to implant them in our bodies, and sow disease and tragedy within our homes.
While looking at the box, it occurred to the author to tie long narrow silk ribbons, highly colored, to ten bats, blind them, and liberate them (believing from previous experiments that, if the distance were not too great, they would go back to their homes), and drive back to the doodle-bug cave to observe their return. This might have added something to the knowledge of their habits; but, on reflection, the author who had willingly faced the dangers of rattlesnakes in dark caves in the interest of science, could not reconcile himself, though the call was strong, to the infliction of that degree of cold and studied cruelty of blinding these little friends of mankind, whom he so dearly loves. Chloroforming, cocainizing, suggested themselves as an incentive, in that they would alleviate the pain to be inflicted in carrying out the experiment. But the dictates of his softer nature prevailed; and, if a small leaf could be added to the garland of science by the display of such cruelty to that beneficent little creature, and name and fame were to be the reward, the author would remain unrewarded.
That there might be no possibility of error in confusing our bats in the box with some belated colony returning home, as they do sometimes come home in mid-summer quite late in the day, the author white-washed the bats in the box by drenching them through the wire meshes with a solution of prepared chalk, to the water of which some gum Arabic had been added to give it adhesiveness. After waiting for a short time for the water in the chalk solution to evaporate, the box was vigorously shaken, in order that they might get their ''motors'' in action; and then the door was opened wide. Remaining with the box long enough to see that the bats were escaping, the time was taken, and the high-powered automobile was raced back to the doodle-bug cave at a rate of speed which disregarded all traffic laws.
For a while during the race the bats could be seen, but after a time the bee-line from field to cave veered from the macadam road, and the bats, being so high, were lost sight of. The 28 or 30 miles from the field to the cave were covered in just fifty minutes. Selecting the best point of vantage with reference to the direction from the field and the wind, the coming of the bats was awaited.
Within eight minutes the vanguard appeared, then the larger numbers, and began dropping from a great altitude as described before, and darting into the side entrance of the cave. As by this time the hot sun and the wind had completely dried the prepared chalk on their bodies, leaving all manner of white stains on a black background, they could have been likened unto numbers of half-clad, or carelessly covered little elves. But they had not only reached their haven of rest through the agency of that wonderful and unfailing endowment such as only Nature can provide, ORIENTATION, but had reached it in safety.
It would naturally suggest itself that some disease would break out among these creatures living as they do, so densely packed, yet in studying a well-tenanted bat-cave with 3 or 4 million bats making it their home, one is surprised at not finding dead bats scattered all over the floor, as surely on the part of some of these, Nature's last debt became due and was paid. A great many of these caves are from 20 to 40 feet high, twice or thrice as wide, and miles in length; yet we may cover hundreds of square feet without finding a single dead bat. People engaged in the business of emptying such caves for commercial purposes declare that bats must be very long lived, as they rarely find a dead bat in the tons of guano they remove from the floor of the cave every year.
As to the longevity of bats, this is quite true. The author has found many specimens perfectly grey, and with the dentine of their molars worn down smooth. As to the age of a bat, that would be hard to determine, but placing it at twenty-five or thirty years would be safe conjecturing. The lamented microscopic luminary, Prof. Elie Metchniekoff, advanced the theory that all creatures without a colon, or large intestine, are very long lived, because they do not have a receptacle in which to harbor enormous bacterial flora, and in which are developed and thrown off the complex chemical substances that bring about old age. This statement applies to the bat, as it has no colonwhich accounts for its longevity.
But our cave owners have not reckoned with the most wonderful of Nature's creation, as bats and a cave are purely a matter of business; for the guano, being the highest grade of fertilizer, finds a ready market, and when the annual crop has been gathered, the bats and their cave in the hum and bustle of commercial life are forgotten until it is time to harvest the next crop. But the student in search of knowledge, and endeavoring to unravel the skein of Nature's secrets, makes a most startling revelation.
Truly the dead bats are not scattered promiscuously about on the floor of the cave, nor are they covered by the guano that is being constantly deposited. No, a little close scrutiny will reveal the fact that all the dead bats are found in one little heap, in some dark corner of the cave. The colony has selected a resting place for its departed brothers.
That this observation, so startling and uncanny, is not in error, is evidenced by the fact that the little bones are in one heap, perfectly intact. If the bats had been caught and taken to that spot by some wild animal, some of the delicate bones would be missing or scattered about. Very many skulls can be counted in the little bat cemetery. In the Mitchell's Lake Bat Roost where the author and owner has tens of thousands of bats, the extreme southwest corner of the Roost has been selected as the last resting place.
What emotions, pathetic or tragic, might be found in a cave or Roost among a little bat family! Is emotion, one of the faculties of the higher intellect, brought into play when they reverently select a place for their departed brothers? Surely it is not for hygienic reasons, as the dead are not remote from the living, but remain in the same surroundings, and the decomposition of their little bodies would not be any more detrimental to the health of the living than the constantly decomposing guano, their own excretory product. This is indeed most astounding and perplexing, for it is almost inconceivable that this creature, so low in the scale of life, should possess cerebral faculties which cross the boundary life of instinct into the glorious, God-given realm of REASON.
In their natural homes, caves, is where the bat suffers the greatest loss, particularly to their young. The baby bats from the time they are born cling mechanically to the mother, as she builds no nest to rear her young. The mother bat, in her long nocturnal search for food, carries her babies with her. Truly a burden added to motherhood! The author during the summer of 1915 caught a red bat mother "Nyctinomus nevoboracencis," who had five babies clinging to her body. She seemed to know them individually, as she allowed them all to take their turn at nursing; when she thought one had had enough, she would push the one nursing off with her nose, the hungry one being close at hand to take the nipple that had just been vacated, and in that manner she apparently was rearing her burdensome family in great contentment. She truly was a mother and had her burdens to bear, as her five babies weighed 253 grains, and she, the burden bearer, weighed only 191 grains. This species of bat, I do not believe, is gregarious.
The high ceiling of a cave to which the bats cling and roost is one of the features that cause them to make it their home, as it protects them from wild animals. A cave with a low ceiling, no matter how inviting otherwise it might be, is certain not to be tenanted by bats, even if its mouth be situated on the face and in the middle of a high vertical cliff, where it would be impossible for any wild animal to reach. This unquestionably is an inherited instinct, as it involves one of the most potent features in the continuance of the species, viz., the protection of its progeny.
Bats have the remarkable faculty of being able to compress themselves into very narrow spaces. In fact, the space is limited only to the median diameter of their heads, which is about 5/16 of an inch. The sternum or breast bone is well adapted to this flattening facility; and to insure it against injury in the act of taking advantage of this faculty for its protection, Nature has placed the testicles of the bat in the abdominal cavity, and has thoroughly covered the reproductive organs on the outside of that cavity with a long prepuce. It is quite obvious that the animal's anatomy should harmonize with its habits; and this gives us another view of the faultless works of Nature. If the reproductive organs were placed on the outside of the abdominal cavity, they would perhaps become injured in the bat's struggling to compress itself into a small opening; and the resultant injury to that important organ would mean an interference with the continuance of the species. Dame Nature, sometimes herein referred to as "The Old Lady,'' is infallible; she makes no mistakes. This avenue of defense is directed for its protection against one of its most formidable enemies, the chicken snake.
Coons, opossums, wild cats, skunks, civet cats, and all kinds of snakes are the bats' principal terrestial enemies, but these are found in caves only for a short time during certain months, after the babies are born. They well know that it would be useless for them to try to obtain food in a bat cave at any other time, and they not only know the propitious season, but they also know the ease with which it can be obtained.
As said before, the baby bats cling mechanically to the mother with the clawed feet, hooked thumb, and a tuft of hair in their mouths; and when the mother returns to the cave after her long and burdened nocturnal pilgrimage in search of food, she is well-nourished and better fitted to continue her maternal functions, but sorely in need of the rest and sleep she finds in her home. Her wings, now having so admirably served the physical, become mantles of love as she wraps her baby in their velvety embrace, knowing the danger that lurks underneath, and goes to sleep.
Like all babies, human and other kinds, when its "tummy" is full, it also will go to sleep. Here is where it will often loosen its hold; and, as it has no cradle or nest to rest in, it falls to the floor of the cave on the soft guano, but, by spreading its little wings, it manages to break the fall so as not to injure itself. This awakens the mother bat, who, finding her precious charge missing, immediately darts down to the floor over which it flutters and scrambles in a very awkward manner, usually finding many babies, but halting only for a second or two at each one, to ascertain if it is hers, until she finds her own, which she does with unequivocal certainty. Then with a few caressing licks on its naked little body, and perhaps uttering words such as can be articulated only by the divine promptings of motherhood, she causes her little babe again to cling to her, and then she flies back to her place and safety.
But here again we see Old Dame Nature asserting her inexorable laws, as she causes some of her other creatures, the wild animals, to lurk in the cave awaiting just such contingencies, in order to catch and devour not only the defenseless baby bats that fall to the floor but also the mothers who come down after them.
A BAT SLAYER SLAIN
When camping near a bat cave to study these creatures at first hand, a very rare opportunity was afforded the author to witness one of the tragedies that befall these valuable little mammals in their homestragedy, as it appears to us, but in truth merely the promptings of Nature, the dictates of whose implacable laws find no association with kindness, pity, or cruelty.
It is impossible for one to look directly upward in a bat cave, on account of the great numbers of bats hanging so densely to the ceiling and continually dropping guano and urine; but this cave afforded excellent facilities for observation, in that a niche, or recess, resembling somewhat a bay window in the vertical wall, formed by a large piece of stone which had detached itself and fallen inward, made an excellent retreat. From this point of vantage the eye could sweep the cave in one direction as far as the darkness would permit, and in the opposite direction to the mouth, some thirty-five or forty feet distant. Here one could sit by the hour, observing these most peculiar creatures, away from the excretory showers, and with a reasonable degree of comfort, as the observation point was near enough to fresh air to overcome somewhat the ammoniacal gases, at least to the point of tolerance.
The entrance to the cave commences with a descent at an acute angle from the surface of the low hill to a depth of about twenty-five feet, where the mouth proper begins, the entire opening in the ground being about thirty feet in diameter. The emergence of the bats toward evening and their return in the morning had been noted from the outside and from the mouth of the cave; and the author, being desirous of observing their behavior in the cave immediately after their return in the morning, stationed himself in the mentioned niche long before daylight, so as to await the coming of the bats. The outlines of the rim of the crater leading to the mouth could be plainly discerned from the inside by the starlight.
After an hour of patient waiting, the monotony of intense stillness was broken by the sound of the loosening of small stones, and on looking in the direction of the rim, the figure of a large wild cat was made out. As he half turned to begin his descent, the outlines of his head were seen, then his tail last, the occasional faint sound of a loosened stone indicating that he was making for the inside of the cave. How far he had entered, of course, could not be told, as his steps became perfectly noiseless on account of his soft paws, and the soft and yielding guano. The thought of being associated with a wild animal in a close place, and in inky darkness, was not very pleasant, particularly when its course or direction was not known. The author, however, was provided with a sawed-off shot gun loaded with buck shot, which gave him every assurance of safety, as marksmanship with such a weapon at short range is quite an unnecessary accomplishment, its results being unfailing.
However, with eyes and ears wide open, the stillness being almost painful, patience was beginning to become a grind, and threatening to overthrow the enthusiasm for original scientific research, held in leash only by the delightful anticipation of the uncertainty of coming events. Conjectures of all kinds floated through the long dark vigil for daylightfear lest some little noise, sneeze, or cough might scare away the creature whose presence promised so much. Would his sense of smell tell him of the presence of an enemy? Would his keen ears hear the human breathing? The long-wished-for time began to send in little, dim rays of light, which became gradually brighter, until the fortunate sight was afforded of the cat, with its head opposite to the niche, crouched down, and like his fellow visitor, awaiting the return of the bats. This was most pleasing, indeed, because of the assurance of perfect observation of the cat's behavior, as he would not be frightened away by seeing an enemy. It even appeared to relieve the soreness induced by a cramped position.
The vanguard of the returning tenants soon appeared, closely followed by the great army, and to one of the trespassers, they were very welcome, as each little private caused a little complement of fresh air to follow it, the lack of which was beginning to be sorely felt. To this great army the cat paid no heed whatever, well knowing his inability to reach the incoming bats, as they flew but a few feet below the twenty-five foot ceiling.
But neither idle curiosity, nor the spirit of investigation brought him there; he came in quest of food, as doubtless he had often come before, and he knew that all he had to do was to bide his time. He did not have long to wait, for shortly after all the bats had entered the cave, and each one had found its place, the chattering gradually ceased, and, with the exception of a few noisy ones who perhaps had some argument to settle, all again were still, and Morpheus reigned supreme.
Presently a baby bat fell to the floor of the cave within a few feet of the cat; it made a short leap and placed its paw upon it, making no attempt to devour it, but looking rather upward as if in expectancy. He was not in the least disappointed, as in a very short time the mother bat, in obedience to that angelic instinct, Motherhood, came down seeking her baby, when the cat got her, and she paid the extreme penalty with that resignation only mothers know. Why didn't the cat immediately devour the defenseless little baby bat? Did he know that the mandates of maternal love would send the mother down after her baby, and so held it captive under his paw? He evidently did. Overwhelmed with a wave of rage at the sight, and hearing the little bones crunched, with words intended for its requiem, but which are not generally used on such occasions, the spectator arose from his crouching position, and gave the cat as he was running for the inclined entrance, the contents of one barrel of the gun, which very effectively ended his career as a mother-and-baby-eater.
After the commotion among the sleeping inmates brought about by the shot had subsided and quiet again ruled, quite a number of baby bats were seen to fall to the floor of the cave, and the mothers to dart down after them and pick them up. Prom the number observed to fall, the cat would unquestionably have had a bountiful feast, as doubtless he had often had before.
Is this great destruction of the most valued friend of man one of Nature's schemes in continuing her alleged "balance?" It may be so, or it may not, but the fact remains that countless thousands, perhaps millions, of these arch enemies of the fiend of the insect world serve as food to other creatures, while to us they are purveyors of health, and the death of only one represents the distinct loss of one sanitary worker. We are truly in need of all of these creatures that Nature can provide, and it consequently behooves us to employ our God-given gift of REASON to disturb that "balance" in our own favor by putting an end to such destruction. Can this be done ? Yes, it can; and we need no long nor expensive experimentation to ascertain this fact, for the method has long passed the experimental point and become a settled fact, as we shall see later on.
A great many dissections have revealed the fact that the love-making season for bats begins about the middle of April, and that the babies are born about the end of June or the first days in July. Procuring specimens from one place, dissections were made every two or three days, up to and including the 14th of April. For reasons over which the author had no control, no more dissections were made until the 28th of April, when all the females were found pregnant from the very earliest stages, to the size of the fetus shown in the photograph, which with all certainty can be said to be about 14 days old.
For a few days before, during, and after the babies are born, an "affaire domestique" takes place in the lives of these creatures, whether in their natural or artificial homes, that is not only most interesting and peculiar, but grippingly perplexing.
In a bat roost where tens of thousands make their home, they seek the innermost and darkest places which have been provided for them for just this purpose, and keep perfectly quiet. Not a sound of their high squeaky voices is to be heard; they also have laid aside for the time being their quarrels and their fussy nature. In a cave, where literally millions make their home, the same conditions obtain; they seek the darkest places in the cave, sometimes perhaps a mile from the mouth. Some few will fly out very early in the morning, 2 or 3 o'clock, and remain on the wing only for an hour or so, perhaps to quench their thirst in the dew-laden air; but, on returning, they make not the slightest noise. As no wild animal or snake ever goes into a cave for any great distance beyond the mouth, from these they are well protected; but it seems that it is not so much for protection that they seek these dark hiding places, as it is to convert them into lying-in quarters.
But why should ALL resort to these quarters? "What role, if any, does the male, or papa bat, play at this particular time? If he has any to perform, we could understand that he should join his mate and be a solace and source of comfort during her trials. But there are many who are not papas, or even prospective papas, and but very remotely, or not at all, kin to the new arrivals, and could have no interest in their welfare; these would be perfectly safe in the forepart of the cave where they usually find their place during all of the feeding season, except for these few days. Wherein does silence become so vital or so essential to the welfare of the home? That it serves a purpose is unquestioned, as it is prompted by the implacable dictates of Nature.
This perplexing trait exhibited by the bat about the time the young are born occasioned a very pleasing and amusing incident. A stockman who has in the hills of his extensive pasture a very large and lucrative bat cave, happened to be looking after his cattle in the vicinity thereof; and, it being toward evening, it was perfectly natural that he should glance in the direction of the cave for the flying bats, as these creatures were a source of revenue to him without carrying any overhead expense, and were more certain than the cattle. He saw no bats. Consulting his watch, he grew apprehensive, as it was time for the flight. To allay his fears, he rode up to the mouth of the cave; but, truly, not a bat was to be seen. Dismounting, in order to make a closer inspection, he went into the cave a short distance and listened for quite some time. The longer he listened the denser the stillness became, and the more his anxiety grew.
As darkness was fast approaching, he rode back to the ranch house in a very crestfallen mood, brooding over the loss of the millions of his little friends who contributed so bountifully toward those whose happiness was his. What was the matter? How did it happen? What had caused this exodus?
With the "hope that springs eternal," etc., he consoled himself with the thought that perhaps the bats had all flown out before he reached the brow of the hill from which he made his first observation. However, the prospective loss of seventy-five tons of bat guano, that most valuable of all fertilizers, which his cave yielded him annually was not so easy to banish from his mind. Mental pictures of the thick black columns of bats, as he had so often seen them leave the cave, coupled with the regrets for financial certainty of the never-failing guano crop to meet plans and obligations carefully laid, but now ruthlessly swept away, made a very restless and sleepless night for him. He "eagerly wished the morrow," that he might be at the cave before daylight, and get "surcease of sorrow" at the entrance of his financial shrine.
Long hours before the first rays of the peep of day found our friend seated on the outside of the cave; and, as daylight approached, his hopes instead of the bats, found their place in the darkness of the cave. One more little hope! Perhaps the bats came in during the night? Again he went into the cave, deeper than the evening before, emerging entirely resigned to his fate. His bats were gone. Hastily arranging matters about the ranch for a few days' absence, he came to the city to call on the author and tell him about his great loss. His sad story, told with a most woeful face and long drawn out, was patiently and respectfully heard, the listener assuming the role of a deeply-sympathizing friend; but when the feigned sympathy could no longer be controlled, the author broke out in a most uproarious laugh, at which his friend was not only amazed but took deep umbrage. Thinking the joke had been carried far enough, the author then informed his friend that not only did he have all the bats he ever had, but a wonderful increase. The ranchman's joy then knew no bounds; he jumped from his chair with the enthusiasm of a boy, and promised the author one of the finest country dinners, if it proved true that his bats were simply having their babies. As to the Texas "cowman," his word is an integral characteristic; and it is needless to say that a magnificent repast was enjoyed by all who attended the "baptismal feast" an entertainment that will long be remembered.
Some day the author means to build a bat roost, of course strictly according to the known successful plans, but he will have a secret "observatory" constructed on the inside for his own use, in order to be able actually "to move and have his being" if not "live" among these wonderful friends of mankind, and to get a more intimate acquaintance with their home life by careful study. If a second edition of this book is ever to be written, the author hopes to answer therein many perplexing questions which must now be left to the conjectures of the reader.
The first instance of the real practical value of bats as destroyers of mosquitoes, particularly the night or malarial ones, came under the author's observation in his private practice, and served greatly to encourage his enthusiasm for the continued study of these wonderful creatures.
About five miles from the City of San Antonio in a westerly direction is a farm irrigated by an elevated wooden tank and windmill, and also a big earthen tank holding a large amount of standing water. Scattered about the farm were many one-inch leaky faucets creating as many little pools of stagnant water. Bach of these large tanks and the many little pools formed ideal mosquito-breeding places; but in them there were also bred thousands of dragon flies of many varieties. These could be seen disporting themselves all day long.
During the years of 1906 and 1907, this farm was tenanted by a widower and his two little girls, aged 12 and 15 years respectively, and in the summer they slept on cots on the galleries of the house without even thinking of mosquitoes, mosquito bars, or screens, for they never heard the singing of a mosquito about the place. In the early part of 1908, a portion of this farm was rented to a tenant whose family consisted of himself, his wife, and four grown children. A very high barn on the place was renovated by the new tenants, and the lower floor was converted into living rooms. One evening in the early spring, noticing that a large number of bats were coming out from under the roof of the barn, the tenant and his family proceeded to kill the bats, and prided themselves on having destroyed "over two washtubfulls of the pesky critters." Soon afterwards, the old tenant and his little girls found they could not sleep as formerly on the open galleries, as the place was swarming with mosquitoes; and his children and those of the new tenant were soon ill with a severe type of malarial fever. The mosquitoes came only at night, beginning with sundown. It is plainly evident that the dragon flies held down the diurnal mosquitoes during the day, but the destruction of all of the bats had left the night mosquitoes unmolested, hence the malarial infection naturally followed.
WIDE EXTERMINATION OF MOSQUITOES
As mosquitoes are the chief article of diet of bats, particularly the nocturnal varieties which convey malaria, these animals must be reckoned as the arch enemy of the insect; and, as the mosquito is man's arch enemy, the bat ought to receive the highest recognition as a valuable hygienic agent. In order to ascertain approximately how many mosquitoes a bat would destroy in its nocturnal wanderings in one night, the following experiment was carried out: Knowing of a hunter's small cabin some ten miles from the city where bats were congregating, the author procured two large white sheets and spread them on the floor of the cabin about 4 o'clock in the morning, and awaited the coming of the bats. The roosting places had, however, been stuffed with rags so that they could not roost out of the range of the area of the sheets. A careful watch was made of the number of bats going in; and the count was verified from the inside of the cabin. Then they were left alone, but counted again in the evening as they flew out. After noting that the same number went out as were counted going in, the many pellets of guano that had accumulated on the sheets were carefully collected, placed in a small pill box, and the sheets again spread out, to continue the experiment the next day. This was done three times consecutively, with the result that the count averaged 26 pieces of guano for each bat. Having ascertained approximately how many times a bat dropped guano during the day or its resting hours, one dropping or single piece of guano was macerated in peroxide of hydrogen for several days. The peroxide dissolved the oxidized and concreted mucus holding the little mass of guano together; this was then filtered through ordinary filter paper, the weight of which had previously been accurately ascertained, and the residue found contained principally the comminuted skeletons of mosquitoestheir probosces, heads, legs, wings, thoraces, abdomens, and scales. The external body of the mosquito, being of the horny substance already defined as chitin, affords the bat no nutrition; for it is absolutely insoluble and hence passes through the alimentary canal undigested as fecal debris. The weight of this filtered residue of one bat-dropping, was approximately 1/25 of a grain.
One hundred mosquitoes that had never been engorged, i. e., which had been raised from the eggs, then, after being hatched and kept under netting all of the time, had been allowed to starve, were thoroughly dried and were comminuted by being rolled over and over by a half-inch steel ball in a porcelain dish. They weighed, after being macerated in peroxide of hydrogen as was the guano, approximately 2/5 of a grain. It follows then that every dropping of the bat contains approximately the skeletal remains of ten mosquitoes. This much of the experiment is correct; and, if we continue the figures in accordance with the findings, we shall see that the bat must be credited with consuming in one night, as represented by the number of pieces of guano it drops during its resting hours, 260 mosquitoes. Without any further investigation on this point, due to the correctness of the experiment, the author at the time accepted these figures; but from the extraordinary reports made to him by the tenants of the Mitchell's Lake lands as to the disappearance of malaria, and from his own observations of this fact and of the large diminution of mosquitoes, he was led to conclude that he was not giving the bat its just deserts; in fact, was materially underestimating its great hygienic value. The immense clouds of mosquitoes that used to come down on the tenants in the work of irrigating at night, which phenomenon they described as "like being bombarded with handfuls of bran," had unquestionably disappeared, but the conditions under which they bred had not changed one iota. There was nothing that could have brought about this modified condition except the great increase in the number of bats. None appreciated the changed conditions more than the tenants of these lands; and we are bound to concede that these people who live there year in and year out are really the best and most competent judges of the conditions and environments of the locality where they live.
Again, enlisting the services of his old, faithful friend, the author made very many observations during the late summer and fall of the year 1917, and continued the said observations during the summers and falls of 1918, 1919, and 1920, and the summer of 1921. The results thereof place the bat on the high pedestal of preventive medicine as a most wonderful hygienic agent, and account satisfactorily for the eradication of malaria and the changed conditions at Mitchell's Lake.
It will be recalled that the Mitchell's Lake bat roost was erected on these lands on account of the ideal conditions for the propagation of mosquitoes and malaria which exist there; and, as said before, no swamp in the low lands could possibly be worse. The entire sewage of the City of San Antonio, amounting to 15,000,000 gallons daily, finds its way into this lake.
The observations were extended over the five years mentioned, on account of the extreme difficulties encountered in their making. Specimens of bats were obtained only between the hours of 9 p. m. and 3 a. m. Many and many an entire night was passed without procuring a single specimen. If some enthusiastic student should care to carry on this work with a view toward its verification or improvement, he will appreciate the difficulties under which he must labor.
PROOF OF BATS' MEALS
When the bats return to their roost in the morning, which is usually about 4:45 o'clock, and sometimes much later, they can be easily captured, but it will be found that there is little or no food in the stomach. The stomachic digestion, which is very rapid, has completed itself, and the pellets which the bat voids during the day represent the food which was undergoing the intestinal digestion when it reached home. The blood from the mosquitoes' abdomens or their albuminous internal organs, if it should have been caught unengorged, is rapidly digested, leaving only the chitinous insoluble hulls, which are so thoroughly comminuted by the sharp chopping teeth and the rapid mastication that they require the low power of the microscope to be seen.
In the course of the five years mentioned, the many specimens procured were marked with the time of capture, and on return to the work room were carefully dissected, the stomachic and intestinal contents being painstakingly weighed, or else placed in a solution of formaldehyde until that could be conveniently done. Without going into the details of this tedious, expensive, and laborious experiment, extending over the years mentioned, the results as found were, that the minimum of the stomachic and intestinal contents weighed 18 grains, and that the maximum of the same weighed 42 grains. Thirty grains, therefore, is the average weight of food the bat consumes in one night's feeding. To be very conservative in arriving at the approximate number of mosquitoes a bat will consume in one night's foraging, let us deduct fifty per cent (50%) of this weight as being due to moisture. This will leave us 15 grains.
In one of the preceding paragraphs, we have seen how and under what conditions the weight of one hundred mosquitoes was ascertained, and that it amounts to 2/5 of a grain. It follows, then, that the fifteen grains represent the weight of 3,750 mosquitoes, consumed by one bat in one night. For additional conservatism, let us deduct ten per cent for food other than mosquitoes, which would be small, plant-sucking insects, leaving us a grand total of 3,375 mosquitoes. When it is taken into consideration that the experiment from which these figures are derived, represents the food ingested by the bat from the hours of nine o'clock at night until three o'clock in the morning, we enhance the conservatism by not taking into account the ingested food after three o'clock in the morning.
It would be very conservative to estimate the number of bats as permanent residents at the Mitchell's Lake bat roost at two hundred and fifty thousand, though when the period of migration is well established the number could be just as conservatively estimated at more than half a million. If the reader will take a slip of paper and pencil and do a little multiplying as per figures given above, he will be astounded and amused at the results he obtains. The estimation of the food of bats other than mosquitoes, given at ten per cent, is arrived at in a very singular but convincing manner, and is furnished by the guano itself.
If we will take indiscriminately a quantity of guano, just as it is found in the hopper of a bat roost or on the floor of a cave, toward the end of the feeding season, and make from it many little heaps, each containing by very careful count one hundred pellets of guano, we shall be astonished at the regularity with which we find each little heap to contain ten dull, straw-colored pieces of guano or pellets, readily distinguished from the ninety ordinary, coal-black ones. Of course, some of the hundred heaps will contain more and some less of these dull-colored pellets, but the averaged ten per cent remains constant.
As the bats feed on mosquitoes, and mosquitoes feed on blood, it is but natural that the excrement or guano of bats should be black, because it is the iron in the blood that imparts the black color. In fact, the enormous iron content in bat guano affords a most convincing argument as to the food, as has been shown by chemistry. The dull, straw-colored pellets represent the skeletal remains of insects other than mosquitoes, that carry no blood, hence contain no iron, and therefore do not give the pellets the black color.
However, this ten per cent deviates during the first month of the feeding season, which begins in this climate, about the 15th of February (San Antonio, Texas, Latitude 29° 27' northLongitude 98° 28' west of Greenwich).
For many years past, the author has observed that three things happen simultaneously in this vicinity, with almost clock-like regularity. The mosquitoes emerge, the swallows arrive, and the bats begin to fly, their feeding season having begun. This happens on February 15-16th, hardly later than the 17th. For the first month of the bats' feeding season the guano pellets do not exhibit the ten per cent of dull, straw-colored pellets, the percentage then being barely three. The reason for this is that mosquitoes begin their flight before other insects develop in the new year, and hence are correspondingly more plentiful. As a verification of this observation, a chemical analysis of the guano dropped during this time shows one-eighth of a pound of iron more to the ton than does that dropped during the rest of the year.
The photo marked "Mosquitoes and Guano" shows how "identical ground mosquitoes and ground bat guano are. The one on the right is pulverized guano, and the one on the left is ground mosquitoes.
This most interesting feature revealed in bat guano opens to the student a wide field in determining the nature of the food of bats, other than mosquitoes, and which may bring added nobility to this most wonderful of Nature's creatures. The author has been at work on this feature in the scatology of bats for quite some time, and hopes some day to find evidence of such a nature as will win for the bats encomiums galore. It will be possible to demonstrate that in addition to this wonderful creature's habits in preventing sickness and tragedy in homes, and increasing man's crops, it puts more dollars in his pockets by protecting his fruit.
In this connection, the author quotes the gist of a letter he received some time ago from a gentleman in California. The letter in some manner became misplaced, and if this little volume falls into his hands, he will recall the correspondence, and will, it is hoped, again communicate with the author. The letter was occasioned by the writer's seeing an article on bats in a newspaper. His words in addition to being laudatory of the author's work, gave information to the effect that a brother of the writer has an extensive orchard in British Guiana, in a region noted for fruit growing. To encourage the fruit industry, the Government offers a prize for the orchard showing the greatest freedom from pernicious insects. The previous year his brother won the said prize; but his neighbors some two miles in each direction, who worked as hard as he did, to keep their orchards in fine condition, not only were not so rewarded, but one of them had his orchard condemned. The brother orchardist, after very careful observation, ascribed the freedom of his orchard from pernicious insects to the activities of a colony of bats that made one corner of an old barn on the premises their home. This incident, like the incident of the bats in the high barn on the irrigated farm previously mentioned, and which gave the author such an encouraging and helpful clue, might well afford a valuable hint to the American orchardist.
Can the reader imagine a more valuable possession than a well-tenanted bat roost on his farm or country place? To begin with, his family is protected against that form of tragedy presented by disease, with the concomitant suffering, anguish, anxiety, and perhaps mourning. But he doesn't keep all this protection to himself; his neighbors, perhaps less fortunate than he in the possession of this world's goods, share it with him; and what a proud satisfaction he must enjoy in the knowledge that these neighbors and their little children are enjoying the same protection with him, while in the hopper of his bat roost there is accumulating the agent that will more than double the output of his vegetable garden, and not only furnish food for the fruit trees in his orchard, but also rid them of the pernicious insects that hinder them from being healthy and bountiful-bearing !
That bats must have a selective instinct for finding the engorged mosquito is in no better way shown than by the enormous and almost unbelievable quantity of blood they consume. This is indicated by the iron the guano contains. This unassailable point is demonstrated by no experience, observation, or experiment the author might have made, but by that cold-blooded branch of science, known as chemistry. Any one with an elementary knowledge of inorganic chemistry can prove it; and it will give positive information. In the analysis appear two technical termshemoglobin, which is the red coloring matter of the red corpuscle, and chitin (pronounced ki-tin) already defined in Allegation One. The analysis is founded on the fact that hemoglobin contains 0.42 of one per cent of iron, and that blood contains 15 per cent of hemoglobin. As the analysis is quite pertinent to the study of the spleen, the reader will find it given here in after tinder the heading, "FUNCTIONS OF THE SPLEEN."
In ALLEGATION FOUR it is stated that the Mitchell's Lake bat-roost will average a production of two tons of guano annually. Analysis reveals the fact that two tons of bat guano represent about 6,350 pounds of liquid blood. Yes, but this is only the guano dropped in the roost during the day, while the bats are resting. Is it not good reasoning to assume that the bats that make the Mitchell's Lake roost their home drop as much more guano during the night whilst feeding, which guano is scattered broadcast in their aerial flight? This means that the myriads of tenants of this little building consume in one year some 12,700 pounds of liquid blood. Figures run riot when we attempt to compute the number of mosquitoes these bats must catch (each to provide a tiny drop of blood in its little abdomen), in order to collect and digest more than six and one quarter tons of liquid blood. After one seriously attempts to make such a computation, the eradication of malaria ceases to appear to him such a wonder.
It would naturally suggest itself that an excrementitial product, comprising such an 'enormous quantity of blood, would be an ideal breeding place for myriads of house flies, and, by the continual burrowing of its larvae, keeps the these noxious insects. Such, however, is not the case, as flies do not breed in bat guano.
A small brown bug, the name of which the author does not know, as if to contribute to the general good of a bat roost, finds a home and food in the guano, where it breeds in large numbers and serves several useful purposes. It adds nitrogen to the guano, breaks up the pellets into powder, which makes the spreading of the fertilizer a matter of 'ease, and, by the continual burrowing of its larvae, keeps the guano level, and allows the hopper in the roost to become evenly filled.
The roost is, indeed, a very complicated structure, embodying all the different features demanded by Nature and found in a well-tenanted cave, a flying space, a hanging space, and a hibernating space, being the essential features. A "lost space" involved in the construction is also very profitably utilized.
As our country grows in population, agricultural areas must be opened up; in fact great irrigation projects have recently been inaugurated, and many more are in contemplation. "While irrigation means increases and practical certainty of crops, it also means mosquitoes, and mosquitoes mean malaria. No irrigation can be carried on without creating, or at least leaving, small water holes or puddles in which mosquitoes will breed.
The farm house and the cabins for the farm hands may be well screened; this will afford some protection against malaria; but, at some time during the season, the water allotment or the condition of the crops will make it imperative for the irrigation to be done at nightand thus the protection afforded by the screening is rendered nil, as the farmhand becomes infected with malaria, which causes him to lose fifty per cent of his efficiency.
In the cultivation of rice, no artificial methods for the eradication of malaria are of any avail, as ideal conditions for the propagation of mosquitoes are created by man himself in the cultivation of that crop, thereby most effectively aiding and abetting Nature in the continuance of her schemes, which she has surrounded with immutable laws.
The preceding dissertation concludes and answers ALLEGATION TWO.
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