What use are these minute details, noted hour by hour? Why these puerilities? What matters to us the industry of a wretched grub, hardly known even to the professional experts?
Well, these puerilities involve the most weighty problems that we are privileged to discuss. Is the world an harmonious creation, governed by a primordial force, a causa causarum? Or is it a chaos of blind conflicting forces, whose reciprocal [[263]]thrusts produce a chance equilibrium, for better or for worse? Minute entomological details examined with some thoroughness, may serve us better than syllogisms, in the scientific investigation of these trifles and others like them. The humble Cionus, for its part, tells us of a primordial force, the motive power of the smallest as of the greatest things.
A day is not too long to give the bladder a good lining. Next day the larva moults and passes into the nymphal state. Let us complete its story with the data gleaned in the fields. The cocoons are often found on the grass near the food-plant, on the stalks and dead blades of the Gramineæ. Generally, however, they occupy the little twigs of the mullein, stripped of their bark and withered. The adult insect emerges sooner or later in September. The gold-beater’s-skin capsule is not torn irregularly, at random; it is neatly divided into two equal parts, like the two halves of a soap-box.
Has the enclosed insect gnawed the casing with its patient tooth and made a fissure along the equator? No, for the edges of either hemisphere are perfectly clean-cut. There must, therefore, have been a circular line ready to facilitate the opening. All that the insect had to do was to hunch its back and give a slight push, in order to unfasten the roof of its cabin all in one piece and set itself free.
I can just see this line of easy rupture on certain [[264]]intact capsules. It is a faint line ringing the equator. What does the insect do beforehand to contrive that its cell shall open in this way? A humble plant, flowering early in the spring, the blue or scarlet pimpernel, has also its soap-box, its pyxidium, which splits easily into two hemispheres when the time comes for the seed to be scattered. In either case it is the work of an unconscious ingenuity. The grub does not plan its methods any more than the pimpernel: it has hit upon its ingenious scheme of joining the halves of its capsule by the inspiration of instinct alone.
More numerous than the capsules which burst accurately are others which are clumsily torn by a shapeless breach. Through this some parasite must have emerged, some ruthless creature which, unacquainted with the secret of the delicate joint, has released itself by tearing the gold-beater’s-skin. I find its larva in cells which are not yet perforated. It is a small, white grub, fixed to a discoloured tit-bit which is all that remains of the Cionus’ nymph. The intruder is sucking dry the rightful occupant, whose budding flesh is still quite tender. I think I can identify the murderess as a bandit of the Chalcid tribe, which is addicted to such massacres.
Her appearance and her gluttonous ways have not misled me. My rearing-jars provide me with abundant supplies of a small bronze-coloured [[265]]Chalcid with a large head and a round, tapering body, but with no visible boring-tool. To inquire her name of the experts will not help me much. I do not ask the insect, ‘what are you called?’ but ‘what are you able to do?’
The anonymous parasite hatched in my jars has no implement similar to that of the Leucospis,[2] the chief of the Chalcididæ; it has no probe which is able to penetrate a wall and place the egg, at some distance, on the food-ration. Her germ, therefore, was laid in the very flanks of the Cionus’ larva, before the latter had built its shell.
The methods of these tiny brigands appointed to the task of thinning out the too numerous are extremely varied. Each guild has its own method, which is always horribly effective. How should so small a creature as the Cionus cumber the earth? No matter: it has to be massacred, to perish in its cradle, a victim of the Chalcid. Like other creatures, the peaceful dwarf must furnish its share of organizable matter, which will be further and further refined as it passes from stomach to stomach.
Let us recapitulate the habits of the Cionus, very strange habits in an insect of the Weevil series. The mother entrusts her eggs to the swelling capsules of the scallop-leaved mullein. So far, everything is according to rule. Other Weevils, as a matter of fact, prefer, when setting [[266]]their children up in life, the pods of some other mullein, or those of the figwort or of the snap-dragon, two plants belonging to one and the same botanical family. But now we are suddenly confronted with the strange and exceptional. The mother Cionus chooses the mullein with the smallest capsules, whereas in the neighbourhood and at the same season there are others loaded with fruit whose dimensions would provide spacious lodgings and abundance of food. She prefers dearth to plenty and narrow to spacious quarters.