Neither is it thinking of the outer enemy when it bores down to the skin when the pea is intact, and then stops short.  It suddenly stops because the innutritious skin is not to its taste.  We ourselves remove the parchment-like skins from a mess of pease-pudding, as from a culinary point of view they are so much waste matter.  The larva of the Bruchus, like ourselves, dislikes the skin of the pea.  It stops short at the horny covering, simply because it is checked by an uneatable substance.  From this aversion a little miracle arises; but the insect has no sense of logic; it is passively obedient to the superior logic of facts.  It obeys its instinct, as unconscious of its act as is a crystal when it assembles, in exquisite order, its battalions of atoms.

Sooner or later during the month of August we see a shadowy circle form on each inhabited pea; but only one on each seed.  These circles of shadow mark the doors of exit.  Most of them open in September.  The lid, as though cut out with a punch, detaches itself cleanly and falls to the ground, leaving the orifice free.  The Bruchus emerges, freshly clad, in its final form.

The weather is delightful.  Flowers are abundant, awakened by the summer showers; and the weevils visit them in the lovely autumn weather.  Then, when the cold sets in, they take up their winter quarters in any suitable retreat.  Others, still numerous, are less hasty in quitting the native seed.  They remain within during the whole winter, sheltered behind the trap-door, which they take care not to touch.  The door of the cell will not open on its hinges, or, to be exact, will not yield along the line of least resistance, until the warm days return.  Then the late arrivals will leave their shelter and rejoin the more impatient, and both will be ready for work when the pea-vines are in flower.

To take a general view of the instincts in their inexhaustible variety is, for the observer, the great attraction of the entomological world, for nowhere do we gain a clearer sight of the wonderful way in which the processes of life are ordered.  Thus regarded, entomology is not, I know, to the taste of everybody; the simple creature absorbed in the doings and habits of insects is held in low esteem.  To the terrible utilitarian, a bushel of peas preserved from the weevil is of more importance than a volume of observations which bring no immediate profit.

Yet who has told you, O man of little faith, that what is useless to-day will not be useful to-morrow?  If we learn the customs of insects or animals, we shall understand better how to protect our goods.  Do not despise disinterested knowledge, or you may rue the day.  It is by the accumulation of ideas, whether immediately applicable or otherwise, that humanity has done, and will continue to do, better to-day than yesterday, and better to-morrow than to-day.  If we live on peas and beans, which we dispute with the weevil, we also live by knowledge, that mighty kneading-trough in which the bread of progress is mixed and leavened.  Knowledge is well worth a few beans.