Remark that the peas touch at the sides, where they are pressed one
against the other. The grub seeking the point of attack cannot move
about at its ease. Remark also that the lower pole rests upon the
umbilical excrescence and opposes to any attempt at boring difficulties
which do not exist in the parts protected by the skin alone. It is even
possible that this umbilicus, which is differently organized, contains
special juices distasteful to the little larva.
This, beyond a doubt, is the secret of the peas exploited by the
Bruchus and yet remaining fit to sprout. They are injured but not dead,
because they are invaded in the free hemisphere, the part which is at
the same time easier to enter and less easy to wound. Moreover, as the
whole pea is too much for a single grub, the loss of substance is
reduced to the piece preferred by the consumer; and this piece is not
the essential part of the pea.
Given other conditions, with seeds either very small or exceedingly
large, we should see the results changing entirely. In the first case,
the germ would be gnawed like the remainder and would perish by the
tooth of the too niggardly served grub; in the second case, the
abundant food would allow of several guests. The common vetch and the
broad bean, exploited in the absence of the pea, tell us something in
this connection; the smaller seed, devoured all but the skin, is a ruin
whose germination we may expect in vain; the larger, on the contrary,
despite the Weevil’s numerous cells, is still capable of sprouting.
Admitting that the number of eggs on the pod is always much greater
than that of the peas contained, and that, on the other hand, each pea
is the exclusive property of one grub, we wonder what becomes of the
surplus. Do these larvæ perish outside, when the more precocious have
taken their places one by one in the leguminous larder? Do they succumb
to the intolerant teeth of the early occupants? They do neither. Let us
set forth the facts.
On all old peas, now dry, from which the adult Weevil has issued,
leaving a gaping hole, the magnifying-glass reveals a varying number of
fine, reddish-brown dots, perforated at the centre. What are these
spots, of which I count five or six or even more on a single pea? There
is no mistake possible: they are the entrance-points of so many grubs.
Several workers have therefore penetrated into the seed; and of the
whole gang only one has survived, waxed big and fat and attained the
adult age. And the others? We shall see.
At the end of May and in June, during the laying-season, inspect the
still green and tender peas. Nearly all the seeds invaded show us the
multiple dots which we already observed on the dry peas abandoned by
the Weevils. Does this actually mean an assembly of guests? Yes. Skin
the aforesaid seeds, separate the seed-lobes, subdivide them if
necessary. We discover several larvæ, very young, bent into a bow, fat
and wriggling, each in a little round hollow in the heart of the
victuals.
Public-domain text, read in full here on John Shaqi.
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