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.