The larvæ soon appear and develop rather quickly. They are naked, cylindrical grubs, dull white, curved into a hook like the Dung-beetles’, but without the knapsack in which the latter reserve the cement for plastering the interior of the emptied loaf and preserving the victuals from desiccation. The head is powerful and glossy black; there is a brown streak on either side of the first [[66]]thoracic segment; the legs and mandibles are strongly made.
Classed close beside the Dung-eaters, the Trox-beetles form a genus of boorish habits, far removed from the domestic fondness of the Scarabæus, the Copris[4] and the others. With them there are no longer provisions stored away beforehand, no rations kneaded for the larva’s benefit. The least industrious of the Dung-beetles, the Onthophagi,[5] for example, pack into the bottom of a pit a short sausage, selected from the best part of the exploited heap; in the dish thus provided they contrive a hatching-chamber, in which the egg is daintily lodged. Thanks to the mother’s care, often, also, to the father’s, the new-born grub finds itself provided with all it could wish. It is a privileged creature, spared the asperities of life.
The Trox, on the other hand, has a harsh and pitiless training. The grub has to find board and lodging at its own cost and peril, a serious question even for a consumer of Fox-dung. The mother scatters her eggs [[67]]under the furry ordure. Her foresight in the interest of her young goes no further. The cake that nourishes her will feed her family likewise. It is large and will be enough for all.
In order to follow the first actions of the grubs, I set apart a few eggs, singly, in a glass tube. At the bottom is a column of moist sand; above this is a store of food taken from that part of the Vulpine excrement which is richest in Rabbit’s fur. Hatched by day, the grub at first attends to its lodging. It digs, hollowing itself a retreat in the sand, a short, vertical shaft into which a few scraps of the fostering felt are dragged afterwards. As and when the provisions are consumed, the grub returns to the surface to collect more.
The manœuvres of the grubs in the chief establishment, the earthenware pan with the wire-gauze cover, begin and are continued in the same fashion. Under cover of the heap exploited in common, the larvæ have dug themselves a vertical shaft apiece, the length of a man’s finger and the diameter of a thick pencil. At the bottom of the dwelling there is no mass of victuals stored up in advance, such as the abundance on the surface would [[68]]permit. Instead of hoarding, the Trox-larvæ live from day to day, I surprise them, above all in the evening, discreetly climbing to the top, scraping the heap above their pit, collecting a shaggy armful and immediately climbing down again tail foremost. They do not reappear so long as the little bale of fur holds out. When their provisions are finished and their appetite returns, they make a fresh ascent and a fresh collection.
This frequent coming and going in the shaft threatens sooner or later to bring down the sandy wall. Here we see renewed the industry of the Geotrupes couples, who have a way of plastering the wall of their pit with dung in order to avoid its collapsing while the material of the huge sausage is being amassed on repeated journeys; only, with the Trox, it is the larva itself that undertakes the work of consolidation. From end to end it lines its gallery with the same felt on which it feeds.
In three or four weeks’ time, all the hairy materials of the heap have disappeared underground, dragged by the larvæ to the bottom of their burrows. On the surface of the soil nothing is left except the remains [[69]]of the bones. The adults have gone to earth and are dead or dying. Their time is over. I obtain the first nymphs at midsummer. A glass receptacle shows them to me slowly turning round and round and polishing with their backs the earthy wall of their cell, a simple, oval cavity.
By the middle of July the perfect insect has matured. Not yet defiled by the dirt of its calling, it is really magnificent in its ebony cuirass, its strings of large beads surmounted by white hairs, its hinder and middle tarsi shod with bright red. It comes up to the surface, finds the Fox’s dejecta, settles down and from now onward is a filthy scavenger. Once torpid in the sand, under the heap of ordure which serves it as a roof, it will pass the winter there and resume its labours in the spring.
When all is said, the Trox is a somewhat uninteresting insect. One single point in her history deserves to be remembered, namely, her predilection for what the Fox’s stomach has refused. I know another instance of these peculiar tastes. The Owl, when he has caught a Field-mouse, stuns her with a blow of his beak on the back of the neck and swallows her whole. It is for the [[70]]digestive pouch to bone and skin her and sift the bad from the good. When the selection is made—as it is, most admirably—the bird, with a shrug of its body, gets rid of the indigestible stuff; it vomits a pellet of bones and fur. Now, just like the furry mass evacuated by the Fox, these balls of filth have their votaries. I have just seen one of them at work. This is the Choleva tristis, Panz., a dwarf related to the family of the Silphæ.
Is the fur of a Rabbit or a Field-mouse such a very precious thing, then, that it has special exploiters appointed to work at it again after the Fox’s intestine and the Owl’s crop have been unable to break it up and use it? Yes, this fur has a certain value. Nature’s treasury claims it for fresh purposes with such an imperious voice that our own industries, which in their fashion are endowed with a terrific power, of digestion, cannot guarantee us the protracted possession of what was a scrap of fluff.