The Sacred Beetle, and Others

by Jean-Henri Fabre

Let us come down to plain facts. The Copris’ pill is a more or less pronounced ovoid, sometimes differing but slightly from a sphere in shape. It is not quite so pretty as the work of the Gymnopleurus, which is very nearly pear-shaped, or at least reminds one of a bird’s egg, notably a Sparrow’s, because of the similarity in size. The Copris’ work is more like the egg of a nocturnal bird of prey, of any member of the Owl family, as its projecting end does not stand out conspicuously.

From this pole to the other the ovoid measures, on an average, forty millimetres, by thirty-four across.[5] Its whole surface is tightly packed, hardened by pressure, converted into a crust with a little earth grained into it. At the projecting end, an attentive eye will discover a ring bristling with short straggling threads. Once the egg is laid in the cup into which the original sphere is hollowed, the mother, as I have already said, gradually brings the edges of the cavity together. This produces the projecting end. To complete the closing, she delicately rakes the ovoid and scrapes a little of the material upwards. This forms the ceiling of the hatching-chamber. At the top of this ceiling, which, if it fell in, would destroy the egg, the pressure is very slight indeed, leaving an area devoid of rind and covered with bits of thread. Immediately under this circle, which is a sort of porous felt, lies the [[153]]hatching-chamber, the egg’s little cell, which easily admits air and warmth.

Like the Sacred Beetle’s egg and those of other Dung-beetles, the Copris’ egg at once attracts attention by its size, but it grows much larger before hatching, increasing two- or threefold in bulk. Its moist chamber, saturated with the emanations from the provisions, supplies it with nourishment. Through the chalky porous shell of the bird’s egg, an exchange of gases takes place, a respiratory process which quickens matter while consuming it. This is a cause of destruction as well as of life: the sum total of the contents does not increase under the inflexible wrapper; on the contrary, it diminishes.

Things happen otherwise in the Copris’ egg, as in the other Dung-beetles’. We still, no doubt, find the vivifying assistance of the air; but there is also an accession of new materials which come to add to the reserves furnished by the ovary. Endosmosis causes the exhalations of the chamber to penetrate through a very delicate membrane, so much so that the egg is fed, swells and enlarges to thrice its original volume. If we have failed to follow this progressive growth attentively, we are quite surprised at the extraordinary final size, which is out of all proportion to that of the mother.

This nourishment lasts a fairly long time, for the hatching takes from fifteen to twenty days. Thanks to the added substance with which the egg has been enriched, the larva is already pretty big when born. We have not here the weakly grub, the animated speck which many insects show us, but a pretty little creature, at once sturdy and tender, which, happy at being alive, arches its back and frisks and rolls about in its nest. [[154]]

It is satin-white, with a touch of straw-colour on its skull-cap. I find the terminal trowel plainly marked: I mean that slanting plane with the scalloped edge whereof the Sacred Beetle has already shown us the use when some breach in the cell needs repairing. The implement tells us the future trade. You also, my attractive little grub, will become a knapsacked excreter, a fervent plasterer manipulating the stucco supplied by the intestines. But first I will subject you to an experiment.

Now what are your first mouthfuls? As a rule I see the walls of your nest shining with a greenish, semifluid wash, a sort of thinly-spread jam. Is this a special dish intended for your delicate baby stomach? Is it a childish dainty disgorged by the mother? I used to think so when I first began to study the Sacred Beetle. To-day, after seeing a similar wash in the cells of the various Dung-beetles, including the uncouth Geotrupes,[6] I wonder whether it is not rather the result of a mere exudation accumulating on the walls in a sort of dew, the fluid quintessence filtering through the porous matter.

The Copris mother lent herself to observation better than any of the others. I have many times surprised her at the moment when, hoisted on her round pill, she excavates the top in the form of a cup; and I have never seen anything that at all suggests a disgorgement. The cavity of the bowl, which I lose no time in examining, is just like the rest. Perhaps I have missed the favourable moment. In any case, I can take only a brief glance at the mother’s occupations: all work ceases as soon as I raise the cardboard sheath to give light. Under these conditions the secret might escape me indefinitely. Let us look at the [[155]]difficulty from another angle and enquire whether some special milk-food, elaborated in the mother’s stomach, is necessary for the infant larva.

In one of my cages I rob a Sacred Beetle of her round pill, lately fashioned and briskly rolled. I strip it at one point of its earthy layer and into this clean point I drive the blunt end of a pencil, making a hole a third of an inch deep. I install a newly-hatched Copris-grub in it. The youngster has not yet taken the least refreshment. It is lodged in a cell which in no respect differs from the rest of the mass. There is no creamy coating, whether disgorged by the mother or merely oozing through. What will result from this change of quarters?

Nothing untoward. The larva develops and thrives quite as well as in its native cell. Therefore, when I first started, I was the victim of an illusion. The delicate wash which nearly always covers the egg-chamber in the Dung-beetles’ work is simply an exudation. The grub may be all the better for it, when taking its first mouthfuls; but it is not indispensable. To-day’s experiment confirms the fact.