There are exceptions to this premature end; sometimes the two eggs develop equally well; but such cases are exceptional, so that the Bruchid family would be reduced to about half its dimensions if the binary system were the rule.  To the detriment of our peas and to the advantage of the beetle, the eggs are commonly laid one by one and in isolation.

A recent emergence is shown by a little sinuous ribbon-like mark, pale or whitish, where the skin of the pod is raised and withered, which starts from the egg and is the work of the new-born larva; a sub-epidermic tunnel along which the grub works its way, while seeking a point from which it can escape into a pea.  This point once attained, the larva, which is scarcely a twenty-fifth of an inch in length, and is white with a black head, perforates the envelope and plunges into the capacious hollow of the pod.

It has reached the peas and crawls upon the nearest.  I have observed it with the magnifier.  Having explored the green globe, its new world, it begins to sink a well perpendicularly into the sphere.  I have often seen it half-way in, wriggling its tail in the effort to work the quicker.  In a short time the grub disappears and is at home.  The point of entry, minute, but always easily recognisable by its brown coloration on the pale green background of the pea, has no fixed location; it may be at almost any point on the surface of the pea, but an exception is usually made of the lower half; that is, the hemisphere whose pole is formed by the supporting stem.

It is precisely in this portion that the germ is found, which will not be eaten by the larva, and will remain capable of developing into a plant, in spite of the large aperture made by the emergence of the adult insect.  Why is this particular portion left untouched?  What are the motives that safeguard the germ?

It goes without saying that the Bruchus is not considering the gardener.  The pea is meant for it and for no one else.  In refusing the few bites that would lead to the death of the seed, it has no intention of limiting its destruction.  It abstains from other motives.

Let us remark that the peas touch laterally, and are pressed one against the other, so that the grub, when searching for a point of attack, cannot circulate at will.  Let us also note that the lower pole expands into the umbilical excrescence, which is less easy of perforation than those parts protected by the skin alone.  It is even possible that the umbilicum, whose organisation differs from that of the rest of the pea, contains a peculiar sap that is distasteful to the little grub.

Such, doubtless, is the reason why the peas exploited by the Bruchus are still able to germinate.  They are damaged, but not dead, because the invasion was conducted from the free hemisphere, a portion less vulnerable and more easy of access.  Moreover, as the pea in its entirety is too large for a single grub to consume, the consumption is limited to the portion preferred by the consumer, and this portion is not the essential portion of the pea.