A rough beginning for the feeble mandible, even though the material to be bored through is a fine clay. Other grubs bite at once into a soft bread which surrounds them on every side; this one, on leaving the egg, has to make a breach in a wall before taking nourishment.
Of what use are these obstacles? I do not doubt that they have their purpose. If the grub is born at the bottom of a closed pot, if it has to chew through brick to reach the larder, I feel sure that certain conditions of its well-being demand this. But what conditions? To become acquainted with them would call for an examination on the spot; and all the data that I possess are a few nests, lifeless things very difficult to interrogate. However, it is possible to catch a glimpse of one or two points.
The Gromphas' burrow is shallow; those little cylinders, her loaves, are greatly exposed to drought. Over there, as here, the drying up of the victuals constitutes a mortal danger. To avert this peril, by far the most sensible course is to enclose the food in absolutely shut vessels.
Well, the receptacle is dug in very fine, homogeneous, water-tight earth, with not a bit of gravel, not an atom of sand in it. Together with the lid that forms the bottom of its round chamber, in which the egg is lodged, this cavity becomes an urn whose contents are safe from drought for a long time, even under a scorching sun. However late the hatching, the new-born grub, on finding the lid, will have under its teeth provisions as fresh as though they dated from that very day.
The clay food-pit, with its closely-fitting lid, is an excellent method, than which our agricultural experts have discovered no better way of preserving fodder; but it possesses one drawback: to reach the stack of food, the grub has first to open a passage through the floor of its chamber. Instead of the pap called for by its weakly stomach, it begins by finding a brick to chew.
The rude task would be avoided if the egg lay directly on top of the victuals, inside the case itself. Here our logic is at fault: it forgets an essential point, which the insect is careful not to disregard. The germ breathes. Its development requires air; and the perfectly-closed clay urn does not allow any air to enter. The grub has to be born outside the pot.
Agreed. But, in the matter of breathing, the egg is no better off for being shut up, on top of the provisions, in a clay casket quite as air-tight as the jar itself. Examine the thing more closely, however, and you will receive a satisfactory reply. The walls of the hatching-chamber are carefully glazed inside. The mother has taken meticulous pains to give them a stucco-like finish. The vaulted ceiling alone is rugged, because the building-tool now works from the outside and is unable to reach the inner surface of the lid and smooth it. Moreover, in the centre of this curved and embossed ceiling, a small opening has been made. This is the air-hole, which allows of gaseous exchanges between the atmosphere inside the box and that outside.
If it were entirely free, this opening would be dangerous: some plunderer might take advantage of it to enter the casket. The mother foresees the risk. She blocks the breathing-hole with a plug made of the ravelled vegetable fibres of the Cow-dung, a stopper which is eminently permeable. It is an exact repetition of that which the various modellers have shown us at the top of their calabashes and pears. All of them are acquainted with the nice secret of the felt stopper as a means of ventilating the egg in a water-tight enclosure.
Your name is not an attractive one, my pretty Dung-beetle of the pampas, but your industrial methods are most remarkable. I know some among your fellow-countrymen, however, who surpass you in ingenuity. One of these is Phanæus Milon, a magnificent insect, blue-black all over.
The male's corselet juts forward. On the head is a short, broad, flattened horn, ending in a trident. The female replaces this ornament by simple folds. Both carry on the forehead two spikes which form a trusty digging-implement and also a scalpel for dissecting. The insect's squat, sturdy, four-cornered build resembles that of Onitis Olivieri, one of the rarities of the neighbourhood of Montpellier.