The Glow-Worm and Other Beetles

That finishes the work. The insect will begin all over again under a fresh carcase; for each burrow has one calabash and no more, even as with the Sacred Beetle and her pears.

Here is another of these artists of the pampas. All black and as big as the largest of our Onthophagi,[67 - Cf. The Sacred Beetle and Others: chaps. xi. xvii., and xviii. —Translator's Note.] whom she greatly resembles in general build, Canthon bispinus is likewise an exploiter of dead bodies, if not always on her own behalf, at least on that of her offspring.

She introduces very original innovations into the pill-maker's art. Her work, strewn like the aforementioned with finger-prints, is the pilgrim's gourd, the double-bellied gourd. Of the two stories, which are joined together by a fairly plainly-marked groove, the upper is the smaller and contains the egg in an incubating-chamber; the lower and bulkier is the food-stack.

Imagine the Sisyphus' little pear with its hatching-chamber swollen into a globule a trifle smaller than the sphere at the other end; suppose the two protuberances to be divided by a sort of wide open groove like that of a pulley; and we shall have something very like the Canthon's work in shape and size.

When placed on burning charcoal, this double-bellied gourd turns black, becomes covered with shiny warts that look like jet beads, emits a smell like that of grilled meat and leaves a residue of red clay. It is therefore formed of clay and sanies. Moreover, the paste is sprinkled with little scraps of dead flesh. At the smaller end is the egg, in a chamber with a very porous roof, to allow the air to enter.

The little undertaker has something better to show than her double sausage. Like the Bison Onitis, the Sisyphus and the Lunary Copris, she enjoys the collaboration of the father. Each burrow contains several cradles, with the father and mother invariably present. What are the two inseparables doing? They are watching their brood and, by dint of assiduous repairs, keeping the little sausages, which are in constant danger of cracking or drying up, in good condition.

The magic carpet which has allowed me to take this trip to the pampas supplies me with nothing else worth noting. Besides, the New World is poor in pill-rollers and cannot compare with Senegambia and the regions of the Upper Nile, that paradise of Copres and Sacred Beetles. Nevertheless we owe it one precious detail: the group which is commonly known by the name of Dung-beetles is divided into two corporations, one of which exploits dung, the other corpses.

With very few exceptions, the latter has no representatives in our climes. I have mentioned the little Oval Onthophagus as a lover of carrion corruption; and my memory does not recall any other example of the kind. We have to go to the other world to find such tastes.

Can it be that there was a schism among the primitive scavengers and that these, at first addicted to the same industry, afterwards divided the hygienic task, some burying the ordure of the intestines, the others the ordure of death? Can the comparative frequency of this or the other provender have brought about the formation of two trade-guilds?

That is not admissible. Life is inseparable from death; wherever a corpse is, there also, scattered at random, are the digestive residues of the live animal; and the pill-roller is not fastidious as to the origin of this waste matter. Dearth therefore plays no part in the schism, if the true dung-worker has actually turned himself into an undertaker, or if the undertaker has turned himself into a true dung-worker. At no time have materials for the work been lacking in either case.

Nothing, not the scarcity of provisions, nor the climate, nor the reversed seasons, would explain this strange divergence. We must perforce regard it as a matter of original specialities, of tastes not acquired but prescribed from the beginning. And what prescribed them was anything but the structure.

I would defy the greatest expert to tell me, simply from the insect's appearance and without learning the facts by experiment, the manner of industry to which Phanæus Milon, for instance, devotes himself. Remembering the Onites, who are very similar in shape and who manipulate stercoral matter, he would look upon the foreigner as another manipulator of dung. He would be mistaken: the analysis of the meat-pie has told us so.

The shape does not make the real Dung-beetle. I have in my collection a magnificent insect from Cayenne, known to the nomenclators as Phanæus festivus, a brilliant Beetle in festive attire, charming, beautiful, glorious to behold. How well he deserves his name! His colouring is a metallic red, which flashes with the fire of rubies; and he sets off this splendid jewellery by studding his corselet with great spots of glowing black.

What trade do you follow under your torrid sun, O gleaming carbuncle? Have you the bucolic tastes of your rival in finery, the Splendid Phanæus? Can you be a knacker, a worker in putrid sausage-meat, like Phanæus Milon? Vainly do I consider you and marvel at you: your equipment tells me nothing. No one who has not seen you at work is capable of naming your profession. I leave the matter to the conscientious masters, to the experts who are able to say: I do not know. They are scarce, in our days; but after all there are some, less eager than others in the unscrupulous struggle which creates upstarts.

This excursion to the pampas leans to one conclusion of some importance. We find in another hemisphere, with reversed seasons, a different climate and dissimilar biological conditions, a series of true dung-workers whose habits and industry repeat, in their essential facts, the habits and industry of our own. Prolonged investigations, made at first hand and not, like mine, at second hand, would add greatly to the list of similar workers.

And it is not only in the grassy plains of La Plata that the modellers of dung proceed according to the principles usual over here; we may say, without fear of being mistaken, that the magnificent Copres of Ethiopia and the big Sacred Beetles of Senegambia work exactly like our own.

The same similarity of industry exists in other entomological series, however distant their country. My books give details of a Pelopæus[68 - Cf. The Mason-wasps, by J. Henri Fabre, translated by Alexander Teixeira de Mattos: chaps. iii. to vi. —Translator's Note.] in Sumatra, who is an ardent Spider-huntress like our own, who builds mud cells inside houses and who, like her, is fond of the loose hangings of the window-curtains for the shifting foundation of her nests. They tell me of a Scolia[69 - The chapters on the Scoliæ will appear in More Hunting Wasps. Meanwhile, cf. The Life and Love of the Insect, by J. Henri Fabre, translated by Alexander Teixeira de Mattos: chap. xi. —Translator's Note.] in Madagascar who serves each of her grubs with a fat rasher, an Oryctes-larva,[70 - The larva of the Rhinoceros Beetle. —Translator's Note.] even as our own Scoliæ feed their family on prey of similar organization, with a highly concentrated nervous system, such as the larvæ of Cetoniæ, Anoxiæ and even Oryctes. They tell me that in Texas a Pepsis, a huntress of big game akin to the Calicurgi, gives chase to a formidable Tarantula and vies in daring with our Ringed Calicurgus,[71 - For the Pompilus, or Ringed Calicurgus, cf. The Life and Love of the Insect: chap. xii. —Translator's Note.] who stabs the Black-bellied Lycosa.[72 - For the Narbonne Lycosa, or Black-bellied Tarantula, cf. The Life of the Spider: chaps. i. and iii. to vii. —Translator's Note.] They tell me that the Sphex-wasps of the Sahara, a rival of our own White-banded Sphex,[73 - Cf. The Life of the Fly: chap. i. —Translator's Note.] operate on Locusts. But we must limit these quotations, which could easily be multiplied.

For producing variations of animal species to suit our theorists there is nothing so convenient as the influence of environment. It is a vague, elastic phrase, which does not compromise us by compelling us to be too precise and it supplies an apparent explanation of the inexplicable. But is this influence so powerful as they say?

I grant you that to some small extent it modifies the shape, the fur or feather, the colouring, the outward accessories. To go farther would be to fly in the face of facts. If the surroundings become too exacting, the animal protests against the violence endured and succumbs rather than change. If they go to work gently, the creature subjected to them adapts itself as best it can, but invincibly refuses to cease to be what it is. It must live in the form of the mould whence it issued, or it must die: there is no other alternative.

Instinct, one of the higher characteristics, is no less rebellious to the injunctions of environment than are the organs, which serve its activity. Innumerable guilds divide the work of the entomological world; and each member of one of these corporations is subject to rules which not climate, nor latitude, nor the most serious disturbances of diet are able to alter.

Look at the Dung-beetles of the pampas. At the other end of the world, in their vast flooded pastures, so different from our scanty greenswards, they follow, without notable variations, the same methods as their colleagues in Provence. A profound change of surroundings in no way effects the fundamental industry of the group.

Nor do the provisions available affect it. The staple food to-day is matter of bovine origin. But the Ox is a newcomer in the land, an importation of the Spanish conquest. What did the Megathopæ, the Bolbites, the Splendid Phanæus eat and knead, before the arrival of the present purveyor? The Llama, that denizen of the uplands, was not able to feed the Dung-beetles confined to the plains. In days of old, the foster-father was perhaps the monstrous Megatherium, a dung-factory of incomparable prodigality.

And from the produce of the colossal beast, whereof naught remains but a few rare skeletons, the modellers passed to the produce of the Sheep and the Ox, without altering their ovoids or their gourds, even as our Sacred Beetle, without ceasing to be faithful to her pear, accepts the Cow's flat cake in the absence of the favourite morsel, the Sheep's bannock.

In the south as in the north, at the antipodes as here, every Copris fashions ovoids with the egg at the smaller end; every Sacred Beetle models pears or gourds with a hatching-chamber in the neck; but the materials employed vary greatly according to the season and locality and can be furnished by the Megatherium, the Ox, the Horse, the Sheep or by man and several others.

We must not allow this diversity to lead us to believe in changes of instinct: that would be to strain at a Gnat and swallow a Camel. The industry of the Megachiles, for instance, consists of manufacturing wallets with bits of leaves; that of the Cotton-bees of making bags of wadding with the flock gathered from certain plants. Whether the pieces be cut from the leaves of this shrub or that, or at need from the petals of some flower; whether the cotton-wool be collected here or there, as chance may direct the encounter, the industry undergoes no essential changes.

In the same manner, nothing changes in the art of the Dung-beetle, victualling himself with materials in this mine or that. Here in truth we have immutable instinct, here we behold the rock which our theorists are unable to shake.

And why should it change, this instinct, so logical in its workings? Where could it find, even with chance assisting, a better plan? In spite of an equipment which varies in the different genera, it suggests to every modelling Dung-beetle the spherical shape, a fundamental structure which is hardly affected when the egg is placed in position.

From the outset, without the use of compasses, without any mechanical rolling, without shifting the thing on its base, one and all obtain the ball, the delicately executed compact body supremely favourable to the grub's well-being. To the shapeless lump, demanding no pains, they all prefer the sphere, lovingly fashioned and calling for much manipulation, the globe which is the preeminent form and best-adapted for the preservation of energy, in the case of a sun and of a Dung-beetle's cradle alike.

When Macleay[74 - William Sharp Macleay (1792-1865), author of Horæ Entomologicæ; or, Essays on Annulose Animals (1819-1821), on which I quote the Dictionary of National Biography:] gave the Sacred Beetle the name of Heliocantharus, the Black-beetle of the Sun, what had he in mind? The radiating denticulations of the forehead, the insect's gambols in the bright sunlight? Was he not thinking rather of the symbol of Egypt, the Scarab who, on the pediment of the temples, lifts towards the sky, by way of a pill, a vermilion sphere, the image of the sun?

"He propounded the circular or quinary system, a forcedly artificial attempt at a natural system of classification, which soon became a byword among naturalists." —Translator's Note.

The comparison between the mighty bodies of the universe and the insect's humble pellet was not distasteful to the thinkers on the banks of the Nile. For them supreme splendour found its effigy in extreme abjection. Were they very wrong?

No, for the pill-roller's work propounds a grave problem to whoso is capable of reflection. It compels us to accept this alternative: either to credit the Dung-beetle's flat head with the signal honour of having of itself solved the geometrical problem of preserved food, or else to fall back upon a harmony ruling all things under the eye of an Intelligence Which, knowing everything, has provided for everything.

CHAPTER X

INSECT COLOURING

Phanæus splendidulus, the glittering, the resplendent: this is the epithet selected by the official nomenclators to describe the handsomest Dung-beetle of the pampas. The name is not at all exaggerated. Combining the fire of gems with metallic lustre, the insect, according to the incidence of the light, emits the green reflections of the emerald or the gleam of ruddy copper. The muck-raker would do honour to the jeweller's show-cases.

For the rest, our own Dung-beetles, though usually modest in their attire, also have a leaning toward luxurious ornament. One Onthophagus decorates his corselet with Florentine bronze; another wears garnets on his wing-cases. Black above, the Mimic Geotrupes is the colour of copper pyrites below; also black in all parts exposed to the light of day, the Stercoraceous Geotrupes displays a ventral surface of a glorious amethyst violet.

Many other series, of greatly varied habits, Carabi,[75 - Cf. Chapter XIV (#pgepubid00021). of the present volume. —Translator's Note.] Cetoniæ, Buprestes, Chrysomelæ,[76 - Golden Apple-beetles. —Translator's Note.] rival and even surpass the magnificent Dung-beetles in the matter of jewellery. At times we encounter splendours which the imagination of a lapidary would not venture to depict. The Azure Hoplia,[77 - A genus of Cockchafer. Cf. The Life of the Fly: chap. vii. —Translator's Note.] the inmate of the osier-beds and elders by the banks of the mountain streams, is a wonderful blue, tenderer and softer to the eye than the azure of the heavens. You could not find an ornament to match it save on the throats of certain Humming-birds and the wings of a few Butterflies in equatorial climes.

To adorn itself like this, in what Golconda does the insect gather its gems? In what diggings does it find its gold nuggets? What a pretty problem is that of a Buprestis' wing-case! Here the chemistry of colours ought to reap a delightful harvest; but the difficulties are great, it seems, so much so that science cannot yet tell us the why and the wherefore of the humblest costume. The answer will come in a remote future, if indeed it ever comes completely, for life's laboratory may well contain secrets denied to our retorts. For the moment, I shall perhaps be contributing a grain of sand to the future palace if I describe the little that I have seen.

My basic observation dates a long way back. I was at that time busy with the Hunting Wasps, following their larval development from the egg to the cocoon. Let us take an instance from my notes, which cover nearly all the game-hunters of my district. I will choose the larva of the Yellow-winged Sphex,[78 - Cf. The Hunting Wasps: chap. iv. —Translator's Note.] which, with its convenient size, will furnish an easy object-lesson.

Under the transparent skin of the larva, which has been recently hatched and is consuming its first Cricket, we soon perceive some fine white spots, which rapidly increase in size and number and eventually cover the whole body, except the first two or three segments. On dissecting the grub, we find that these spots have to do with the adipose layer, of which they form a considerable part, for, far from being scattered only on the surface, they run through its whole thickness and are present in such numbers that the forceps cannot seize the least fragment of this tissue without picking up a few of them.

Though perfectly visible without the help of a lens, these puzzling spots call for the microscope if we wish to study them in detail. We then find that the adipose tissue is made up of two kinds of vesicles: some, bright yellow and transparent, are filled with oily drops; the rest, opaque and starch-white, are distended with a very fine powder, which spreads in a cloudy trail when the vesicle containing it is broken on the object-slide. Intermingled without apparent order, the two kinds of bags are of the same shape and the same size. The first go to make up the nutritive reserves, the fatty tissue properly so-called; the second form the white dots which we will study for a moment.

An inspection under the microscope tells us that the contents of the white cells are composed of very fine, opaque grains, insoluble in water and of greater density. The use of chemical reagents on the object-slide proves that nitric acid dissolves these grains, with effervescence and without leaving the least residue, even when they are still enclosed in their vesicles. On the other hand, the true fatty cells suffer in no way when attacked by this acid; they merely turn a little yellower.

Let us take advantage of this property to operate on a larger scale. The adipose tissue taken from a number of larvæ is treated with nitric acid. The effervescence is as lively as if the reaction were taking effect on a bit of chalk. When it has subsided, some yellow clots are floating on the surface. These are easily separated. They come from the fatty substance and the cellular membranes. There remains a clear liquid containing the white granules in solution.

The riddle of these granules was being presented to me for the first time; my predecessors had provided no physiological or anatomical data to guide me; great therefore was my joy when, after a little fumbling, I succeeded in hitting upon their characteristic feature.

The solution is evaporated in a small porcelain capsule, placed on the hot embers. On the residue I pour a few drops of ammonia, or else simply water. A glorious crimson colour at once makes its appearance. The problem is solved: the colouring-matter which has just formed is murexide; and consequently the powdery substance which filled the cells was none other than uric acid, or more precisely ammonium urate.

A physiological fact of this importance can hardly stand alone. Indeed, since this basic experiment I have discovered grains of uric acid in the adipose tissue of the larvæ of all the Hunting Wasps of our parts, as well as in the Bees at the moment of the nymphosis. I have observed them in many other insects, either in the larval or in the perfect state; but in this respect there is none to equal the grub of the game-hunting Wasp, which is all speckled with white. I think I see the reason.

Let us consider two larvæ which eat live prey: that of the Sphex and that of the Hydrophilus.[79 - The Great Water-beetle. —Translator's Note.] Uric acid, the inevitable product of the vital transformations, or at all events one of its analogues, must be formed in both. But the Hydrophilus' larva shows no accumulation of it in its adipose layer, whereas the Sphex' is full of it.

In the latter the duct through which the solid excretions pass is not yet in working order; the digestive apparatus, tied at the lower end, is not discharging an atom. The urinary products, being unable, for want of an open outlet, to flow away as formed, accumulate in the adipose tissue, which thus serves as a common store-house for the residues of the present and the plastic material of the future organic processes. Here something occurs analogous to what we see in the higher animals after the removal of the kidneys; the urea at first contained in the blood, in imperceptible quantities accumulates and becomes manifest when the means by which it is eliminated disappear.

In the larva of the Hydrophilus, on the other hand, the excretions enjoy a free outlet from the beginning; and the urinary products escape as and when formed and are no longer deposited in the adipose tissue. But during the intense labour of the metamorphosis, any excretion becomes impossible; the uric acid must and does collect in the adipose substance of the different larvæ.

It would be out of place, despite its importance, to pursue the problem of the uric residues any further. Our subject is coloration. Let us return to it with the evidence supplied by the Sphex. Her almost transparent larva has the neutral tint of fluid white of egg. Under its fine translucid skin there is nothing coloured, save the long digestive pouch, which is swollen a deep purple by the pulp of the consumed Crickets. But against this indefinite, vitreous background the opaque white uric cells stand out distinctly in their myriads; and the effect of this stippling is a sketchy but by no means inelegant costume. It is skimpy in the extreme, but at any rate it is something.