Finally one of the excavators, favored by the direction taken, attains the central portion.  It establishes itself there, and all is over; the others have only to die.  How are they warned that the place is taken?  Do they hear their brother gnawing at the walls of his lodging? can they feel the vibration set up by his nibbling mandibles?  Something of the kind must happen, for from that moment they make no attempt to burrow further.  Without struggling against the fortunate winner, without seeking to dislodge him, those which are beaten in the race give themselves up to death.  I admire this candid resignation on the part of the departed.

Another condition—­that of space—­is also present as a factor.  The pea weevil is the largest of our Bruchidae.  When it attains the adult stage, it requires a certain amplitude of lodging, which the other weevils do not require in the same degree.  A pea provides it with a sufficiently spacious cell; nevertheless, the cohabitation of two in one pea would be impossible; there would be no room, even were the two to put up with a certain discomfort.  Hence the necessity of an inevitable decimation, which will suppress all the competitors save one.

Now the superior volume of the broad bean, which is almost as much beloved by the weevil as the pea, can lodge a considerable community, and the solitary can live as a cenobite.  Without encroaching on the domain of their neighbors, five or six or more can find room in the one bean.

Moreover, each grub can find its infant diet; that is, that layer which, remote from the surface, hardens only gradually and remains full of sap until a comparatively late period.  This inner layer represents the crumb of a loaf, the rest of the bean being the crust.

In a pea, a sphere of much less capacity, it occupies the central portion; a limited point at which the grub develops, and lacking which it perishes; but in the bean it lines the wide adjoining faces of the two flattened cotyledons.  No matter where the point of attack is made, the grub has only to bore straight down when it quickly reaches the softer tissues.  What is the result?  I have counted the eggs adhering to a bean-pod and the beans included in the pod, and comparing the two figures I find that there is plenty of room for the whole family at the rate of five or six dwellers in each bean.  No superfluous larvae perish of hunger when barely issued from the egg; all have their share of the ample provision; all live and prosper.  The abundance of food balances the prodigal fertility of the mother.

If the Bruchus were always to adopt the broad bean for the establishment of her family, I could well understand the exuberant allowance of eggs to one pod; a rich foodstuff easily obtained evokes a large batch of eggs.  But the case of the pea perplexes me.  By what aberration does the mother abandon her children to starvation on this totally insufficient vegetable?  Why so many grubs to each pea when one pea is sufficient only for one grub?