Worse still. Indifferent to leaving provision for her brood, she nibbles the tender seeds, destroys them, extirpates them, in order to obtain a cavity in the heart of the tiny globule. Into this she slips more or less half a dozen eggs. With the edible substance left, were the whole cell to be consumed, there would not be enough to feed a single grub.
When the bread-pan is empty, the house is deserted. The young abandon their famine-stricken dwelling on the day when they are hatched. They are bold innovators and practise a method which is held in detestation among the Weevils, who are all pre-eminently stay-at-homes: they dare the dangers of the outer world: they travel, passing from one leaf to another in search of food. This strange exodus, unprecedented in a Weevil, is not a mere caprice but a necessity imposed on them by hunger; they migrate because their mother has not provided them with anything to eat. [[267]]
If travelling has its pleasures, enough to make the insect forget the delights of the cell in which it digests at peace, it also has its drawbacks. The legless grub can progress only by a sort of creeping gait. It has no instrument of adherence which will enable it to remain fixed to the twig, whence the least breath of wind may make it fall. Necessity is the mother of invention. To guard against the danger of falling, the wanderer smears itself with a viscous fluid, which varnishes it and makes it adhere to the trail which it is following.
But this is not all. When the ticklish moment of the nymphosis arrives, a retreat in which the grub can undergo its transformation in peace becomes indispensable. The vagabond has nothing of the sort. It is homeless, it sleeps in the open air; yet it is able, when the time comes, to make itself a tent, a capsule, the materials for which are supplied by its intestine. No other insect of its order can build a home like this. Let us hope that the hateful Chalcid, the murderer of nymphs, will not visit it in its pretty little tent.
The grub that lives on the scallop-leaved mullein has shown an utter revolution in the habits of the Weevil clan. The better to judge of this, let us consult a cognate species, placed not far from the Cionus by the classifiers; let us compare the two kinds of life, on the one hand the exception and on the other the rule. The comparison will be all the more useful inasmuch as the new witness also [[268]]exploits a mullein. It is known as Gymnetron thapsicola, Germ.
Dressed in russet homespun, with a plump round body and about the size of the Cionus: there you have the creature. Note the qualifying thapsicola, meaning an inhabitant of the thapsus. On this occasion, I am glad to see, the term could not possibly be happier: it enables the novice to identify the insect exactly, without other data than the name of the plant on which it lives.
The botanist gives the name of Verbascum thapsus to the common mullein, or shepherd’s club, a lover of the tilled fields in both the north and the south. Its bloom, instead of branching out like that of the scallop-leaved mullein, consists of one thick cone of yellow flowers. These flowers are followed by close-packed capsules about as big as a fair-sized olive. Here we no longer have the niggardly pods in which the grub of the Cionus would die of starvation if it did not abandon them as soon as it is hatched; these caskets contain plenty of victuals for one larva and even for two. A partition divides them into two equal compartments, both of them crammed with seeds.
The fancy took me to estimate roughly the mullein’s wealth of seeds. I have counted as many as 321 in a single shell. Now a spike of ordinary size contains 150 capsules. The total number of seeds is therefore 48,000. What can the plant want with such abundance? Allowing [[269]]for the small number of seeds required to maintain the species in a thriving state, it is evident that the mullein is a hoarder of nutritive atoms; it creates foodstuffs; it summons guests to its opulent banquet.
Knowing these facts, the Gymnetron, from May onwards, visits the luxuriant flower-spike and there installs her grubs. The inhabited capsules may be recognized by the brown speck at their base. This is the hole bored by the mother’s rostrum, the aperture needed for inserting the eggs. Usually there are two, corresponding with the two cells of the fruit. Soon the oozings from the cell set hard and dry and obstruct the tiny window; and the capsule is closed again, without any communication with the outer world.
In June and July, let us open the shells marked with brown specks. Nearly always we find two grubs, looking fat as butter, with their fore-parts swollen and their hinder parts shrunken and curved like a comma. Not a vestige of legs, which members would be very useless in such a lodging. Lying at its ease, the grub has plenty of food ready to its mouth: first the tender, sugary seeds; then the placenta, their common support, which is likewise fleshy and highly flavoured. It is pleasant to live under such conditions, motionless and devoting one’s self entirely to the joys of the stomach.