The Life and Love of the Insect

by Jean-Henri Fabre

Well, one of the subjects in my voleries would achieve a similar savage finery if he persisted in his attempts. I speak of Onthophagus Vacca. His nymph has on its forehead a thick horn, one only, bent backward; on its corselet it possesses a like horn, jutting forward. The two, approaching their tips, look like a sort of pincers. What does the insect lack in order to acquire, on a smaller scale, the eccentric ornament of the West-Indian Scarab? It lacks perseverance. It matures the appendage of the forehead and allows that of the corselet to perish atrophied. It succeeds no better than Onthophagus Taurus in its attempt to grow a pointed stake upon its chine; it loses a glorious opportunity of making itself fine for the wedding and terrible in battle.

The others are no more successful. I bring up six different species. All, in the chrysalis state, possess the thoracic horn and the eight-pointed ventral coronet; not one benefits by these advantages, which disappear altogether when the adult splits its case. My near neighbourhood numbers a dozen species of Onthophagi; the world contains some hundreds. All, natives and foreigners, have the same general structure; all most probably possess the dorsal appendage at an early age; and none of them, in spite of the variety of the climate, torrid in [[92]]one place, moderate in another, has succeeded in hardening it into a permanent horn.

Could the future not complete a work the design of which is so very clearly traced? We ask ourselves this the more readily inasmuch as every appearance encourages the question. Examine under the magnifying-glass the frontal horns of Onthophagus Taurus in the pupa state; then consider as carefully the spear upon the corselet. At first, there is no difference between them, except the general configuration. In both cases, we find the same glassy aspect, the same sheath swollen with a crystalline moisture, the same incipient organ plainly marked. A leg in formation is not more clearly declared than the horn on the corselet or those on the forehead.

Can time be lacking for the thoracic growth to organize itself into a stiff and lasting appendage? The evolution of the nymph is swift; the insect is perfect in a few weeks. Could it not be that, though this brief space suffice to promote the maturity of the horns on the forehead, the thoracic horn requires a longer time to ripen? Let us prolong the nymphal period artificially and give the germ time to develop itself. It seems to me that a decrease of temperature, moderated and maintained for some weeks, for months if necessary, should be capable of bringing about this result, by delaying the progress of the evolution. Then, with a gentle slowness, favourable to delicate formations, the promised organ will crystallize, so to speak, and become the spear heralded by appearances.

The experiment attracted me. I was unable to undertake it for lack of the means whereby to produce a cold, even and lasting temperature. What should I have obtained if my penury had not made me abandon the [[93]]enterprise? A retarding of the progress of the metamorphosis, but nothing more, apparently. The horn on the corselet would have persisted in its sterility and, sooner or later, would have disappeared.

I have reasons for my conviction. The abode of the Onthophagus while engaged on his metamorphosis is not deep down; variations of temperature are easily felt. On the other hand, the seasons are capricious, especially the spring. Under the skies of Provence, the months of May and June, if the mistral lend a hand, have periods when the thermometer drops in such a way as to suggest a return of winter.

To these vicissitudes let us add the influence of a more northerly climate. The Onthophagi occupy a wide zone of latitude. Those of the north, less favoured by the sun than those of the south, can, if changing circumstances assist at the time of the transformation, undergo long weeks of a decreased temperature which spins out the work of evolution and ought therefore to permit the thoracic armour, at long intervals and casually, to consolidate into a horn. Here and there, then, the conditions of a moderate, or even cold temperature, at the time of the nymphosis, are realized without the aid of my artifices.

Well, what becomes of this surplus time placed at the service of the organic labour? Does the promised horn ripen? Not a bit of it: it withers just as it does under the stimulus of a hot sun. The records of entomology have never spoken of an Onthophagus carrying a horn upon his corselet. No one would even have suspected the possibility of such an armour, if I had not rumoured the strange appearance of the nymph. The influence of climate, therefore, goes for nothing here. [[94]]

Pushed further still, the question becomes more complicated. The horny appendages of the Onthophagus, of the Copris, of Minotaurus and of so many others are the male’s prerogative; the female is without them or wears them only on a reduced and very modest scale. We must look upon these corniculate products as personal ornaments much rather than as implements of labour. The male makes himself fine for the pairing; but, with the exception of Minotaurus, who pins down the dry pellet that needs crushing and holds it in position with his trident, I know none that uses his armour as a tool. Horns and prongs on the forehead, crests and crescents on the corselet are jewels of masculine vanity and nothing more. The other sex requires no such baits to attract suitors: its femininity is enough; and finery is neglected.

Now here is something to give us food for thought. The nymph of the Onthophagus of the female sex, a nymph with an unarmed forehead, carries on its thorax a vitreous horn as long, as rich in promise as that of the other sex. If this latter excrescence be an incompletely-realized incipient ornament, then the former would be so too, in which case the two sexes, both anxious for self-embellishment, would work with equal zeal to grow a horn upon their thorax. We should be witnessing the genesis of a species that would not be really an Onthophagus, but a derivative of the group; we should be beholding the commencement of singularities banished hitherto from among the Dung-beetles, none of whom, of either sex, has thought of planting a spear upon his chine. Stranger still: the female, always the more humbly attired throughout the entomological order, would be vying with the male in her propensity for eccentric adornment. An ambition of this sort leaves me incredulous. [[95]]