The Sacred Beetle, and Others

by Jean-Henri Fabre

And their hearts swelling with fond hopes, they clinked the sous in their hands. The flattened bullets were forgotten. I saw the children scatter over the plain and begin their search.

On the appointed day, a week later, I returned to the plateau. I was confident of success. My young helpers were sure to have spoken to their playmates of this lucrative trade in Beetle-balls and convinced the incredulous by displaying their earnest-money. And indeed I found a larger party than the first time awaiting me on the spot. They came running to meet me, but there was no burst of triumph, no shout of joy. I suspected at once that things were going badly; and my suspicions were but too well-founded. Many times, after coming out of school, they had hunted for what I had described, but they had never discovered anything like it. They [[34]]handed me a few pellets found underground with the Beetle, but these were simply masses of provisions, containing no larva. I explained matters anew and made another appointment for the following Thursday. Again the search was unsuccessful. The disheartened little hunters were now reduced to quite a small number. I made a final appeal to their sportsmanship and perseverance; but nothing came of it. And I ended by compensating the most industrious, those who had held out to the last, and cancelling the bargain. I had to conduct my own researches, which, though apparently very simple, were in reality extremely difficult.

Many years have passed since then, but even to-day I am without any definite, consistent result after all my digging and exploring, though I have made my examinations at the most likely spots and have carefully watched for favourable opportunities. I am reduced to piecing together my incomplete observations and filling up the gaps by analogy.[2] The little that I have seen, combined with my study of other Dung-beetles in captivity—Gymnopleuri, Copres and Onthophagi—is summed up in what follows.

The ball which is destined to contain the egg is not made in public, in the hurry and confusion of the dung-yard. It is a work of art and supreme patience, demanding concentration and scrupulous care, both alike impossible in the thick of the crowd. One needs solitude in [[35]]order to think out a plan of operations and set to work. So the mother digs in the sand a burrow four to eight inches deep. It is a rather spacious hall communicating with the outer world by a much narrower passage. The insect brings into it carefully selected materials, doubtless in spherical form. There must be many journeys, for towards the end of the work the contents of the cell are out of all proportion to the size of the entrance-door and could not be stored at one attempt. I remember a Spanish Copris who, at the time of my inspection, was finishing a ball as big as an orange at the far end of a burrow whose only communication with the outside was by means of a gallery into which I was just able to insert my finger. It is true that the Copres do not roll pills and do not travel long distances to fetch food home. They dig a hole immediately under the dung and drag the material backwards, armful by armful, to the bottom of their well. They have thus no difficulty in provisioning their houses; moreover, they work in security under the shelter of the manure: two conditions that promote luxurious tastes. The Dung-beetles that follow the humble trade of pill-rollers are less extravagant; and yet, if he cares to make two or three journeys, the Sacred Beetle can amass wealth of which the Spanish Copris might well be jealous.

So far, the Beetle has only raw material, lumped together anyhow. A minute sorting has to take place before anything else is done: this stuff, the purest, is for the inner layer on which the grub will feed; that other, coarser stuff is for the outer layers, which are not meant for food and serve only as a protecting shell. Then, around a central hollow which receives the egg, the materials must be arranged in successive strata, [[36]]according as they are less refined and less nutritive; the layers must possess a proper consistency and must be made to adhere to one another; last of all, the stringy parts of the outer layers, which have to protect the whole structure, must be felted together. How does the clumsy Sacred Beetle, who is so stiff in her movements, accomplish a work of this kind in complete darkness, at the bottom of a hole crammed with provisions and hardly leaving room to stir? When I consider the delicacy of the workmanship and then the rough tools of the worker—angular limbs capable of cutting into hard or even rocky soil—I think of an Elephant trying to make lace. Let whoso can explain this miracle of maternal industry; as for me, I give it up, all the more as I have not had the luck to see the artist at work. We will confine ourselves to describing her masterpiece.

The ball containing the egg is usually the size of an average apple. In the centre is an oval hollow about two-fifths of an inch in diameter. The egg is fixed at the bottom, standing perpendicularly; it is cylindrical, rounded at both ends, yellowish-white and about as large as a grain of wheat, but shorter. The inside of the niche is coated with a shiny, greenish-brown, semifluid material, a real stercoral cream, destined to form the larva’s first mouthfuls. To make this dainty food, does the mother collect the quintessence of the dung? The appearance of it tells me something different and makes me certain that it is a pap prepared in the maternal stomach. The Pigeon softens the grain in her crop and turns it into a sort of milky soup which she subsequently disgorges to her brood. To all seeming, the Dung-beetle displays the same solicitude: she half-digests choice provender and disgorges it in the form of a meat-extract [[37]]with which she lines the walls of the cavity where the egg is laid. Thus the larva, on hatching, finds an easily-digested food, which very soon strengthens its stomach and enables it to attack the underlying strata, which have not been refined in the same way. Under the semi-fluid paste is a soft, well-compressed, uniform mass, from which every stringy particle is excluded. Beyond this are the coarser layers, abounding in vegetable fibres. Finally, the outside of the ball is composed of the commonest materials, but packed and felted into a stout rind.

Manifestly we have here a progressive change of diet. On leaving the egg, the frail grub licks the dainty broth on the walls of its cell. There is not much of this, but it is strengthening and very nutritious. The pap of earliest infancy is followed by the more solid food given to the weaned nurseling, a sort of paste that stands midway between the exquisitely delicate fare at the start and the coarse provisions at the finish. There is a thick layer of it, enough to turn the infant into a sturdy youngster. But now for the strong comes strong meat: barley-bread with its husks, that is to say, natural droppings full of sharp bits of hay. Of this the larva has enough and to spare; and, when it has attained its full growth, there remains an enclosing layer. The capacity of the dwelling has increased with the growth of the occupant, fed on the very substance of the walls; the original little cell with the very thick walls is now a big cell with walls only a few millimetres in thickness; the inner layers have become larva, nymph or Beetle, according to the period. Lastly, the ball itself is a stout shell, protecting within its spacious interior the mysterious processes of the metamorphosis. [[38]]

I can go no farther, for lack of observations; my records of the birth of the Sacred Beetle stop short at the egg. I have not seen the larva, which however is known and is described in the text-books;[3] nor have I seen the perfect insect while still enclosed in its chamber in the ball, before it has had any practice in its duties as a pill-roller and excavator. And this is just what I particularly wanted to see. I should have liked to find the Dung-beetle in his native cell, recently transformed, new to all labour, so as to examine the workman’s hand before it started its work. I will tell you the reason for this wish.

Insects have at the end of each leg a sort of finger, or tarsus as it is called, consisting of a succession of delicate parts which may be compared with the joints of our fingers. They end in a hooked claw. One finger to each leg: that is the rule; and this finger, at least with the higher Beetles and notably the Dung-beetles, has five phalanges or joints. Now, by a really strange exception, the Scarabs have no tarsi on their front legs, while possessing very well-shaped ones, with five joints apiece, on the two other pairs. They are maimed, crippled: they lack, on their fore-limbs, that which in the insect very roughly represents our hand. A similar anomaly occurs in the Onitis- and Bubas-beetles, who also belong to the Dung-beetle family. Entomology has long recorded this curious fact, without being able to offer a satisfactory explanation. Is the creature born maimed, does it come into the world without fingers to its forelimbs? Or does it lose them by accident, once it is given over to its toilsome labours?

One could easily imagine this mutilation to be the result of the insect’s hard work. Poking about, digging [[39]]and raking and slicing, at one time in the gravelly soil, at another in the stringy mass of manure, do not constitute a task in which organs so delicate as the tarsi can be employed without risk. And here is an even more serious matter: when the Beetle is rolling his ball backwards, with his head down, it is with the extremities of his fore-feet that he presses against the ground. What might not happen to the insect’s feeble fingers, slender as thread, in consequence of this continual rubbing against the rough soil? They are merely useless encumbrances; one day or other they seem bound to disappear, crushed, torn off, worn out in a thousand ways. We know unfortunately that our own workmen are all too frequently injured in handling heavy tools and lifting great weights; even so might the Scarab be crippled in rolling his ball, an enormous load to him. In that case his maimed arms would be a noble testimony to his industrious life.