The Scolia's egg is in no way exceptional in shape. It is white, cylindrical, straight and about four millimetres long by one millimetre thick. (About .156 x .039 inch.--Translator's Note.) It is fixed, by its fore-end, upon the median line of the victim's abdomen, well to the rear of the legs, near the beginning of the brown patch formed by the mass of food under the skin.
I watch the hatching. The grub, still wearing upon its hinder parts the delicate pellicle which it has just shed, is fixed to the spot to which the egg itself adhered by its cephalic extremity. A striking spectacle, that of the feeble creature, only this moment hatched, boring, for its first mouthful, into the paunch of its enormous prey, which lies stretched upon its back. The nascent tooth takes a day over the difficult task. Next morning the skin has yielded; and I find the new-born larva with its head plunged into a small, round, bleeding wound.
In size the grub is the same as the egg, whose dimensions I have just given. Now the Cetonia-larva, to meet the Scolia's requirements, averages thirty millimetres in length by nine in thickness (1.17 x .35 inch.--Translator's Note.), whence follows that its bulk is six or seven hundred times as great as that of the newly-hatched grub of the Scolia. Here certainly is a quarry which, were it active and capable of wriggling and biting, would expose the nurseling to terrible attacks. The danger has been averted by the mother's stiletto; and the fragile grub attacks the monster's paunch with as little hesitation as though it were sucking the breast.
Day by day the young Scolia's head penetrates farther into the Cetonia's belly. To pass through the narrow orifice made in the skin, the fore-part of the body contracts and lengthens out, as though drawn through a die-plate. The larva thus assumes a rather strange form. Its hinder half, which is constantly outside the victim's belly, has the shape and fulness usual in the larvae of the Digger-wasps, whereas the front half, which, once it has dived under the skin of the exploited victim, does not come out again until the time arrives for spinning the cocoon, tapers off suddenly into a snake-like neck. This front part is moulded, so to speak, by the narrow entrance-hole made in the skin and henceforth retains its slender formation. As a matter of fact, a similar configuration recurs, in varying degrees, in the larvae of the Digger-wasps whose ration consists of a bulky quarry which takes a long time to consume. These include the Languedocian Sphex, with her Ephippiger, and the Hairy Ammophila, with her Grey Worm.
There is none of this sudden constriction, dividing the creature into two disparate halves, when the victuals consist of numerous and comparatively small items. The larva then retains its usual shape, being obliged to pass, at brief intervals, from one joint in its larder to the next.
>From the first bite of the mandibles, until the whole head of game is consumed, the Scolia-larva is never seen to withdraw its head and its long neck from inside the creature which it is devouring. I suspect the reason of this persistence in attacking a single point; I even seem to perceive the need for a special art in the manner of eating. The Cetonia-larva is a square meal in itself, one large dish, which has to retain a suitable freshness until the end. The young Scolia, therefore, must attack with discretion, at the unvarying point chosen by the mother on the ventral surface, for the entrance-hole is at the exact point where the egg was fixed. As the nurseling's neck lengthens and dives deeper, the victim's entrails are nibbled gradually and methodically: first, the least essential; next, those whose removal leaves yet a remnant of life; lastly, those whose loss inevitably entails death, followed very soon by putrefaction.
At the first bites we see the victim's blood oozing through the wound. It is a highly-elaborated fluid, easy of digestion, and forms a sort of milk-diet for the new-born grub. The little ogre's teat is the bleeding paunch of the Cetonia-larva. The latter will not die of the wound, at least not for some time. The next thing to be tackled is the fatty substance which wraps the internal organs in its delicate folds. This again is a loss which the Cetonia can suffer without dying then and there. Now comes the turn of the muscular layer which lines the skin; now, that of the essential organs;now, that of the nerve-centres and the trachean network, whereupon the last gleam of light is extinguished and the Cetonia reduced to a mere bag, empty but intact, save for the entrance-hole made in the middle of the belly.
>From now onwards, these remains may rot if they will: the Scolia, by its methodical fashion of consuming its victuals, has succeeded in keeping them fresh to the very last; and now you may see it, replete, shining with health, withdraw its long neck from the bag of skin and prepare to weave the cocoon in which its development will be completed.
It is possible that I may not be quite accurate as to the precise order in which the organs are consumed, for it is not easy to perceive what happens inside the exploited larva's body. The ruling feature in this scientific method of eating, which proceeds from the parts less to the parts more necessary to preserve a remnant of life, is none the less obvious. If direct observation did not already to some degree confirm it, a mere examination of the half-eaten larva would do so in the most positive fashion.
The Cetonia-larva is at first a plump grub. Drained by the Scolia's tooth, it gradually becomes limp and wrinkled. In a few days' time it resembles a shrivelled bit of bacon-fat and then a bag whose two sides have fallen in.
Yet this bit of bacon and this bag have the same characteristic look of fresh meat as had the grub before it was bitten into. Despite the persistent nibbling of the Scolia, life continues, holding at bay the inroads of putrefaction until the mandibles have given their last bites.
