THE TWELVE-SPOTTED CUCUMBER BEETLE
(Diabrotica duodecim punctata, Oliv.)
There are few of our insect enemies which do their destructive work more rapidly than do the cucumber beetles. Every child in the South who has left his cucumber hills unscreened knows this, for he has found them some morning literally eaten up over night by the spotted or striped yellow-green cucumber beetles.
The puzzle is, where do they come from so suddenly? It is as though they were waiting for cucumbers to come up, and this is pretty nearly true, for the adults have wintered in the leaves and rubbish of the garden and are all ready to concentrate on the plantlets in the spring.
Unlike so many pests, which are content to trouble us only during a part of their existence, this twelve-spotted cucumber beetle is our enemy all its life long, for it spends its larval life eating the roots of corn and other field crops.
It is a wide-spread pest, with many relatives quite as bad as it is, and not only does it eat up the young and defenseless cucumbers and the roots of the corn, but it is the carrier of a germ infection of a serious nature to the cucumber. My friend, Dr. Erwin F. Smith, informs me that its kind has infested large areas in the South with this disease and dashed the hopes of thousands of boys who, instead of feasting on the melons they have planted with such care, must stand helplessly by and watch the leaves and flowers wilt and the vines decay. It must be remembered that this is a winged carrier of disease and anyone who still fails to understand the speed of travel of an epidemic had better watch the cucumber beetles busy spreading this destructive germ disease. A single beetle feeding on a diseased leaf can carry on its jaws enough germs to infect every melon or cucumber plant in a neighboring field, and that, too, in a single day.
ONE OF THE SAWYERS
(Monohammus titilator, Fab.)
While standing on a street corner waiting for a street-car one day last summer my attention was attracted to this beautiful squirrel-gray creature at my feet. It was so evidently ill that, as I picked it up, I began to examine it to find out what was the matter. Clustered on its neck, out of reach of its feet or jaws were whitish bodies which evidently did not belong to its external skeleton but were probably the eggs of what I took to be some parasite whose growth within the body of the beast had brought about its pitiable condition. These are just visible between the creature’s “horns” in the photograph. It was, in other words, a sick insect.
It is because biologists see these parasites so plainly all down through the scale of living things that they are so sceptical of accepting any other cause of human disease until all possibility has been excluded of its being caused by some parasite or other, too small to be seen even by using the best microscopes.
My sympathy for this long-horned beetle would be keener did I not read that its larval self is spent inside the wood of the pines and firs of our forests, doing great damage to them.
When one is puzzled to know why any living thing should be burdened by such antler-like antennæ, let him remember the peacock’s tail and the bird of paradise’s plumage and be content to know that the laws of evolution are not yet fully known, and that, given time and growth, almost any form can be evolved.
TWO-WINGED INSECTS
(Diptera)
Years ago in Berlin, my German landlady called me in as an expert to decide a controversy between her children and herself as to whether a frog had four legs or six. It seemed strange to me then that a grown-up woman should not know the number of a frog’s legs. Yet there will be many who read these pages who do not know how many wings a fly has. And flies are much more important than frogs.
In fact the mosquito and the house fly, both included in the order of the flies, probably cause more deaths and are more dangerous to human life than any other creatures in the world.
These portraits are of a few only of the vast myriads of forms of two-winged insects which haunt the world. Were I to photograph just one individual of each different species which inhabit the globe, I would have to spend a lifetime doing it, and when it was finished it would make five hundred volumes about the size of this one.
There should never be the slightest difficulty in telling a fly from other insects for there are no other two-winged forms.
Although the flies are sucking insects, their beaks lap up liquid food and are not at all like the beaks of the bugs. In the great majority of flies, the beaks resemble a trunk with curious fleshy folds or lips. It is true some species, like the mosquito, have long, sharp-pointed stylets which, working up and down, puncture the skin of plants and animals.
The larval forms of many flies are maggots, those squirming, often almost headless creatures that abound in rotting carcasses or decaying matter of all kinds, and this is one of the reasons why less is known about the flies than about some others of the insect world which have selected less revolting birthplaces.
Of course, in such a gigantic family no general rules apply, and still, a maggot, whether in an orange or a dead horse, is most likely to be the larva of a diptera or two-winged insect.
THE CRANE FLY
(Limnobia sp.)
Every lover of the autumn woods must have noticed on some still October day, in the little clearings in the woods, these awkward, long-legged flies which, frightened by the approach of a human being, gather their ungainly hind legs together behind and their forelegs in front of them and slowly and laboriously flutter upward into the sunlight. They are well-named, these creatures, “the crane flies,” for their legs are as long and apparently much more useless than those of the crane. In fact some entomologists have expressed themselves as wondering why they have such legs at all for they are so fragile that they break at the slightest touch.
They belong to a family with a thousand species in it and perhaps the most peculiar thing about them is that some forms of the family live and fly about when there is snow on the ground. This is a very rare exception in the insect world.
AN INSECT HAWK: ONE OF THE ROBBER FLIES
(Erax æstuans, Linn.)
Her strong, spiny legs, her powerful body filled with strong wing muscles, and her sharp beak, make this robber fly one of the most dreaded enemies of the other winged insects for, like the hawk among the birds, she pounces on them in their flight and tears them to pieces with her beak, sucking the blood from them as she carries them in the air. A single one of these insect hawks, or robber flies, as they are called, has been known to catch and devour as many as eight moths in twenty minutes.
These robber flies are fearless creatures, for they attack and kill bumble bees and wasps and even, it is said, that monster demon, the dragon-fly. Tiger beetles, too, are said to fall a prey to this insect hawk.
Its other or larval self is also predaceous, boring into beetle larvæ in the ground.
A ROBBER FLY
(Dasyllis grossa, Fab.)
When I learned that this powerfully winged, hairy fly tears beetles’ wings from off their backs with that wedge-shaped beak of hers, and sucks the blood of bees and wasps, it gave me a different idea of the great fly family, which hitherto I had thought was made up of defenseless creatures like the house fly.
Of all the insects we have photographed, few have seemed to be more thoroughly fearless or more ugly than the robber flies. I have never seen one capture and devour a creature larger than itself, but it must be as thrilling an adventure as to see a dragon-fly devour a gnat, or a spider pounce upon the prey entangled in its net.
ANOTHER VIEW OF THE ROBBER FLY
(Dasyllis grossa, Fab.)
At first it looked as though this creature had two heads, one at each end of its body, but the great facet eyes, of which only one can be seen in the photograph, make it clear which is the head and which the egg-laying end of this strange, fearless robber of the air.
Just why it is called a robber fly when it really doesn’t rob at all, but kills, is a mystery to me.
ONE OF THE LARGE ROBBER FLIES
(Mallophora sp.)
This robber fly is not so quick nor so savage as many of its family. It waits for some slow moving insect to come along then pounces upon it.
It probably breeds in decaying wood, although this is not certainly known, and it is very difficult to breed them artificially.
To the economic entomologist the ability to breed these monsters in captivity is one of the most important factors in studying out their life histories, as they are called, their various stages, the plants they feed on, their habits of moulting, of breeding and of feeding their young.
ONE OF THE WORST OF THE ROBBER FLIES
(Deromyia)
This creature is very savage and pounces upon even large sized insects, paralyzing them instantly by a sting of its poisoned beak.
THE CULEX MOSQUITO
(Culex sp.)
The flat white wings of this long-legged creature, vibrating rapidly in the air, make what everyone will agree is the most annoying sound in the world. They make the mosquitos’ hum. The cigar-shaped abdomen is striped like a convict’s jacket. As a boy there was to me a peculiar fascination in watching that abdomen pinken and turn red along its sides as it filled with blood sucked from my hand.
The large eyes compose almost the entire head of a mosquito and in some species they are of an emerald green hue. Straight out in front, close together, curved downward at the tip, are two antennæ furnished with delicate hairs arranged like a bottle brush. With these the creature hears the love hum of its mate and probably scents also the neighborhood of any warm-blooded animal.
Were this a male, instead of a female, these hairs would be much longer and there would be many more of them—they are the smelling organs of the creature and the hearing organs, too, being set into vibration by sound waves of a certain rate. It is important to remember this, for only the females are bloodthirsty. The long, slender proboscis projecting from the head, downward, is furnished with sharp, piercing stylets which, by working up and down, cut their way through the skin. Ordinarily the males and females both are content with sap of plants and fruits as their food, and blood does not seem to be a necessary part of their diet. It is curious that what is supposed to be merely an acquired habit of the female only, of an insignificant little fly, should mean so much to mankind.
Just why a mosquito bite is poisonous is still a matter of question—the suggestion has been made that since both male and female really live on plants, the fluid which the female injects is for the purpose of preventing the plant juice from coagulating during the process of sucking and merely happens to be irritating to warm-blooded animals.
There are three hundred different species of these creatures already described and fortunately this one, a species of culex, is not responsible, so far as known, for the carrying of any human disease.
ONE OF THE HARMLESS ANOPHELES MOSQUITOS
(Anopheles punctipennis, Say)
The malarial mosquito, so called, has spotted wings, but otherwise it looks quite like this harmless form from Maryland. This whole tribe of Anopheles differs from the Culex in the length of its mouth feelers, which project from the base of the proboscis and appear in the photograph almost as long as the proboscis itself, whereas in a photograph of the Culex it would appear so short as to seem merely a thickening of the base of the proboscis.
The wildest fancy of the Arabian story-teller is lacking in imagination compared with the story which the facts of modern science have woven about these tiny representatives of the fly family.
Who could imagine that just because the lady mosquitos, tiring of their usual meal of ripe bananas and plant juices, acquired the habit of sucking blood, vast regions would be devastated and beings millions of times their size would die by thousands. And this, too, not through any real fault of the tiny creatures themselves, but just because some of the persons whose blood they sucked had microscopic wiggling things living in their blood corpuscles, which crawled into the soft throat glands of the mosquito and waited there for a chance to get out into the blood channels of some other human beings.
When one pictures the grief of desolated homes, death-bed agonies of tossing fever patients, the quarantined vessels at anchor in tropical harbors, yellow flagged, with crews dead or dying, the streets of deserted houses from which all life has gone forever through yellow fever and malaria, there is something ghastly in the picture of the winged lady mosquitos flitting airily from pale-faced patients to ruddy-cheeked happy people, unwitting carriers of death.
No conquest of science seems more wonderful in its simplicity and more remarkable in its importance than the discovery that the glands at the base of the mosquito’s bill can become diseased and harbor a microscopic parasite, and transform this merely buzzing, annoying insect into one of the most dangerous creatures alive. To Dr. L. O. Howard, the pioneer of economic entomology, is due the great credit for first showing how this creature can be killed by the use of kerosene on the stagnant waters where the females lay their eggs.
ONE OF THE BEE FLIES
(Sparnopolius fulvus, Wied.)
No butterfly or any other creature of the air could be more beautiful than this dream of early summer. The black velvet body, into which the sunlight sank and disappeared, the fringe of golden hairs along its sides, the steel gray, myriad-facet eyes of which its head was made, and the delicately formed wings, so thin that the light in passing through them was refracted into rainbow tints, made it seem to me more beautiful than almost any of those gorgeous forms of insect life which sometimes fill the clearings in Brazilian forests.
It does seem strange that such a thing as this should live its other life a parasitic grub within the larva of some caterpillar, or in the egg-case of some grasshopper; but so it seems to do. It spends its childhood as a disease, and its mating days as a dainty fly among the nectar-bearing flowers.
ANOTHER OF THE BEE FLIES
(Spogostylum simson, Fab.)
Where you see the carpenter bee you always see these bee flies waiting for the bee to go away from home. When the mother bee is out the female fly goes into the cell of the bee and lays her egg, and when her larva hatches out it eats up the bee’s larva.
LARGE SYRPHID FLY
(Melesia virginiensis, Dru.)
This is a very bright-colored syrphid fly often seen soaring in shadowy places, but what he is doing we do not know. He stays poised in the air and is one of the most beautiful flies we have.
The larvæ of some of the smaller syrphid flies feed upon the larvæ of other insects, aphids in particular; but the larva of this one has never been seen, at least it has never been recognized.
NOT A HOUSE FLY
(Archytas aterrima, Des.)
This portrait of one of the many species of fly, not a house fly, however, is as different as it is possible to be from the maggot from which it grew. The eggs of the mother fly, deposited in some decaying animal matter, hatch in a few days, and out of these eggs come maggots with rudimentary legs and looking like beasts from another world entirely. In a few days more they reach the limit of their growth, and stop, the tissues break down to a mush and out of this mush-like substance are formed flies with wings and sucking, trunklike mouths just like their mothers. The maggots have no sexual organs, and yet, out of the creamy mass of cells, the sexual organs of the flies are formed as though directed by a force as certain in its effects as the law of gravitation.
We have been so intent on killing the fly and so afraid of it as the great carrier of human diseases that we have lost sight of one phase of its character, so to speak. Think of having under our eyes animals like these dipteras from which you can breed a new generation in twelve days! And would it not be strange if, from studying the fly, we should learn the meaning of heredity and sexuality, for this is one of the places where the scientists of the day are at work on the problem of inheritance, that problem which, when elucidated, is likely to make more changes in the world of humankind than almost anything which has so far been discovered. The bearing of the fly on the welfare of the world is one of the most spectacular developments of modern times and a tribute to the value of knowing the minutest details of the world in which we live.
THE HORSE FLY
(Tabanus atratus, Forst.)
The head of the horse fly appears to be all eyes, and it is no wonder that we can so seldom take it by surprise.
Below the oblong, compound eyes are the sharp mouthparts, which in the female are provided with lancets, which enable her to puncture the skin of warm-blooded animals and suck their blood. It is curious that the female should have such habits, while the males are content to lap up nectar from the flowers.
This jet black, loud-buzzing creature flew into my laboratory and made so much noise that I was forced to kill her. This photograph of her is nine times her real diameter.
She belongs to a large and important family of flies, whose females make the lives of men and animals miserable in many parts of the world by their bites, which form most annoying wounds.
A GREEN-HEADED HORSE FLY
(Tabanus punctifer, O. S.)
There are nearly two hundred species of horse flies in North America, and this creature represents one of the commonest forms. It doubtless hatched out somewhere on the edge of the brook which flows through my place in Maryland, and its larval self fed upon other insect larvæ or on the snails and slugs it found itself among.
The bands of iridescent green and copper and purple across its enormous eyes made it a beautiful creature to look upon.
We never used to think the bite of flies was anything worse than annoying, but recently, since we have discovered the danger of letting the germs of disease into the blood streams of our bodies, we have come to see the ghastly possibilities which lie in the piercing mouthparts of these flies. They suck the blood of animals whose blood streams may be swarming with disease germs, and then fly directly to our houses and puncture our skins with a beak covered with these germs which slip off into our veins.
Until we know that the diseases of the birds, and field mice, the coons and ’possums, and all other warm-blooded beasts of a locality are harmless to us, or that it is impossible to transmit them to human beings, it is best to look upon these blood-sucking creatures as winged hypodermic syringes laden with disease.
It has been suggested that the horse flies carry anthrax, and their bites sometimes cause malignant pustules. They are also under suspicion as carriers of infantile paralysis.
FEATHERED INSECTS
(Lepidoptera)
These are peculiarly the feathered fliers of the insect world, for their wings and their bodies, too, are covered with most remarkable one-celled feathers or scales of gorgeous colors which make of some of them the most brilliant of all living things.
Just what these scales are for is not entirely clear, and will not be, perhaps, until we understand the purpose of the gorgeous coloring itself. There is a theory that these scales help to grip the air in flying.
It is a curious coincidence that one of these gorgeously colored creatures should furnish mankind with the material for his own most gaily colored raiment. The silkworm is one of the very few domesticated insects, so to speak, of all the hundreds of thousands of insect species in existence, and a hundred millions of dollars is paid every year for the delicate silk threads unraveled from countless millions of cocoons which the silkworm larvæ have laboriously fashioned around themselves.
To many people, moths are known by what they leave behind—holes in the winter woolens; and butterflies are to them, somehow, things of the sunlight and the summertime. It is worth while to know that these great families of butterflies and moths are not by any means divided equally, that for every family of butterflies there are at least nine of the moths and that the butterflies form but a small proportion of the gaily colored insects of the fields.
Perhaps it makes but little difference to the public, who call them all alike, but it is as easy to tell a butterfly from a moth as it is to tell a lizard from a snake, for all the butterflies have club-shaped feelers, or antennæ, whereas the moths do not, and any child of six can learn to tell the two apart.
No butterfly or moth in its winged state can harm us or our plants. It has no jaws, but keeps itself alive by sucking nectar from the flowers or juices from the fruits or other parts. Its other self, its larva, however, can cause no end of damage. One inconspicuous, brownish form, the codling-moth, no larger than my thumb nail, costs apple growers about ten million dollars every year, while the cabbage moth, the clothes moth, the cutworm and the dreaded gipsy-moth are only a few examples of a gigantic army of voracious larvæ against which man has been struggling ever since he first began to plant seeds in the ground or set out trees for fruit.
LARVA OF THE SWALLOW-TAIL BUTTERFLY OF THE SPICE-BUSH
(Papilio troilus, Linn.)
Is this, I wonder, an insect make-believe, a caterpillar mask, as it were, to frighten away enemies? The black and white eye-spots are not real eyes, but to a bird they doubtless seem so. Its real eyes are inconspicuous points at each side of the head, too small to appear in the photograph.
Few of as stop to think, as the beautiful swallow-tail butterfly, gorgeous in its black and yellow painted wings, flits by us, that it is made of sassafras and spice-bush leaves gathered together and ground up. This monster is a leaf-eating creature, its purpose being the accumulation of food material out of which is made inside of it the gorgeous swallow-tail butterfly. It feeds on sassafras and spice-bush leaves, and when the time arrives makes a nest for itself by fastening the edges of a leaf together. In this nest it passes the winter. When spring comes it breaks open the gray shell of the chrysalis, unfolds a pair of black and gold wings with long tails to them, and flies away in the sunshine in search of flowers and a mate. It is then no more like this monster than an eagle is like a hippopotamus, yet after it has flown about, sucking nectar through its long beak, it mates and lays a mass of eggs, out of which hatch again these strange, weird beings.
FORE PART OF A BROWN BUTTERFLY
(Agrynnis cybele, Fab.)
It is hard to realize that this is the portrait of the head and fore part of a beautiful brown butterfly.
Its head is almost all taken up with the gigantic eyes, which are composed of thousands of tiny facets. The long, trunklike mouth with which it sucks the nectar from the flowers is coiled up like a watch spring. Like shingles on a roof, the scales are fastened in tiers over the broad surface of the wings stretched over the stiff ribs or framework.
The white spots are made by hundreds of white scales and the brown blotches by brown scales, and what these scales are for nobody seems to know. Perhaps they help to grip the wind, for they have running lengthwise of them deep and parallel corrugations so small and fine that were a single scale as large as a lady’s opened fan these corrugations would represent its sticks.
The caterpillar from which this splendid creature came is black, with branching spines, and feeds at night on violets and other plants.
The graceful beauty of the butterfly, its seemingly happy existence, its life among the flowers, where it sips the nectar that the flowers provide, are all a part of common knowledge.
The real life of the butterfly, however, is not so pleasant as we think. Have you ever found a butterfly hanging beneath a leaf on a cold summer morning drenched with dew and stiff with cold? Have you ever seen one trying to cross a field in a rain-storm and observed it vainly attempting to navigate the conflicting air currents? Where do they roost at night and on rainy days? Where do they come from and what becomes of them? These are matters which it has often taken men years to find out, and even now there are many thousands of species of butterflies which are known only by a preserved specimen caught in its flight by the net of some collector.
YELLOW BUTTERFLY
(Colias philodice, Gdt.)
The Doctor Jekyll and Mr. Hyde is so complete between the butterfly which flits over the cabbage patch and the velvety green worm that eats holes in the leaves of the cabbages that it is no wonder that for centuries no connection between the two careers of these creatures, seemingly so far apart, was suspected. In general it is true that no moth or butterfly is injurious to plants except in its larval stage, and herein has lain the clever deception which has doubtless protected these gay mating creatures of the air from the systematic attacks of man until quite recent times.
This picture shows what every boy and girl should know, that every butterfly has club-shaped feelers or antennæ.
It is said of certain species of yellow butterflies that the males give off a pleasing, aromatic odor which is exhaled from the front wings through hundreds of minute, slender scales—scales quite different from those with which the wings and body are covered. This scent, which is so strong that it can be detected by even our blunted olfactory organs if we rub the wings between thumb and forefinger, is supposed to attract the females in some way that is little understood. As among these particular butterflies the male seeks out its mate, it is difficult to understand why it should be the male which has the perfume, since it does not serve to tell the female where her mate is to be found. The inference is that in some way the perfume charms the female.
In some species it is the females which give off an odor, and in either case the distances over which these odors extend and are detected by the males or females respectively are analogous to the inconceivable reach of wireless telegraphy. And who knows but the mechanism of these creatures is set to respond to the swiftly traveling ions which make wireless telegraphy possible?
A BABY OF THE SKIPPER BUTTERFLY
(Eudamus tityrus, Fab.)
There is something fascinatingly strange to me in the babies of the winged butterflies, and I wonder why so many people have an aversion for them? Can there be an instinctive fear of anything that crawls, or is not this fear taught us by unthinking persons? The child is not afraid of the wide-mouthed naked little birds in the nest, or the little blind pink mice, and certainly they are no more innocent looking than the brilliant colored larva of the butterflies or moths.
What helpless things these babies are! They cannot fly, they cannot fight, they can barely see, and even their gait is a hobbled one.
Their business is to eat, and their jaws must keep busy pretty constantly to fill their stomachs with leaf fragments, for the greater part of the soft, flabby bodies is stomach. They are males and females but which they are you cannot tell until they turn into butterflies.
Along this creature’s sides, like portholes in an ocean liner, are the breathing pores, nine in number. Most animals which live on land take air in through a single opening into a great cavity through which the blood circulates and is purified, but the caterpillars, and all insects in fact, instead of circulating their blood in and out of a pair of lungs, have, running through their bodies, a labyrinth of air passages, all connected with the outside air by means of breathing pores.
This caterpillar’s eyes are poor affairs, and unless you look closely you will not find them, for they are merely a few raised spots, like blisters, beneath the skin on either side of its jaws.
It has, like the spiders, a spinneret and a reservoir of liquid silk with which, as it outgrows its baby state, it can spin its own arbor of tough silk fibers and hide itself from view while it is changing to a butterfly. If in late summer you will put one of these creatures in a tumbler and watch it for a day or two, you can see it plainly through the glass pouring out the liquid silk in a steady stream, waving its head from side to side. The silk comes from a spinneret which is just behind the jaws and is about the color of thin starch paste. The way it loops back upon itself and flows in curves reminds me most forcibly of the way the pastry cook, with frosting in a paper cornucopia, writes one’s name upon a birthday cake.
A BUTTERFLY’S MUMMY CASE
One of the most marvelously beautiful of all living creatures lies waiting within this case for the resurrection day, when growth shall split open this polished casket and it shall feel the wings, close packed for weeks, unfold, and, stretching to a hundred times their size, bear it away into the sunshine.
Did the Pharaohs, I wonder, or their wise men, seeing this, model their mummy cases after those which the butterflies make?
This is the chrysalis of a butterfly, that wonder of poets since poetry began, that life-stage of the butterfly which our faith and hopes make comparable to our own rest in the tomb from which man in all ages has believed there came a resurrection and another life, no more to be compared with this than the butterfly’s own existence among the flowers is to be likened to his crawling one upon the leaves. And because the minds of many men in seeking to understand, have broken down this beautiful analogy by finding that there is no real decay within the chrysalis, we must not hence conclude they have done more than brush away a fancied similarity. The mystery remains.
If you should open this butterfly mummy case, lay bare the mummy as it were, you would find a pair of wings in process of formation, a head, a curled-up sucking beak, legs and embryo antennæ, that is, providing it were near the resurrection time. If not, and you had broken in too early, the greater part within the case would be a semi-fluid mass of broken down cell tissues from which the legs and wings and all the other parts are made.
The portholes along the side lead deep into the body and are probably as necessary to the growing butterfly inside as they are to it when it once emerges. The chrysalis must breathe.
To many people there is much confusion as to what is a chrysalis and what a real cocoon. Every cocoon is a silken case spun by the caterpillar in which it can securely hide while it changes first into the chrysalis and then into its winged and final form. This chrysalis, or pupa, forms within the body skin and some caterpillars do not spin a cocoon at all, but merely rest somewhere away from view, until this strange process has been completed within the out-worn shell. This photograph is of such a chrysalis.
A MOTH
We commonly picture the moths and butterflies with their wings spread out or else upright in the air, but many moths trail their wings when they alight and escape our notice by their quiet colors. Walk through the grass and you will frighten thousands which, when they alight again, you cannot for the life of you detect upon the grass stems.
There are hardly any butterflies that trail their wings like this and not one of them has beautiful feathery antennæ.
NOT GOOD TO EAT
Have you never wondered at the temerity with which certain of these slow-moving, helpless creatures expose themselves to the attacks of their enemies? In a world so full of hungry, winged beings it does seem strange, and when the markings are black and white or some such striking color in contrast with the leaves or bark the temerity seems even more extraordinary, until one learns the simple fact—these creatures are not very good to eat.
Not good enough to eat! Supposing that the fly and the mosquito were equipped with some flavor distasteful to the insectivorous birds; if cattle were not good to eat, nor sheep, nor hogs, nor any living, breathing things, what a change there would be in a world like ours! And yet to chemists there is very little difference between some compounds that are good to eat and others that are deadly poison, no greater than that between the poison bitter almond and the sweet one of our dinner table.
One cannot help but wonder why it is that when the border-land twixt food and poison is so narrow in the chemistry of the living cell that every creature has not equipped itself with prussic acid enough to preserve itself from its enemies.
While this protection holds good against many predaceous creatures, there are various birds and even snakes that have found this particular caterpillar not too bad to eat.