Among other things, knowledge tells us:  “The seedsman need not go to the expense of waging war upon the weevil.  When the peas arrive in the granary, the harm is already done; it is irreparable, but not transmissible.  The untouched peas have nothing to fear from the neighborhood of those which have been attacked, however long the mixture is left.  From the latter the weevils will issue when their time has come; they will fly away from the storehouse if escape is possible; if not, they will perish without in any way attacking the sound peas.  No eggs, no new generation will ever be seen upon or within the dried peas in the storehouse; there the adult weevil can work no further mischief.”

The Bruchus is not a sedentary inhabitant of granaries:  it requires the open air, the sun, the liberty of the fields.  Frugal in everything, it absolutely disdains the hard tissues of the vegetable; its tiny mouth is content with a few honeyed mouthfuls, enjoyed upon the flowers.  The larvae, on the other hand, require the tender tissues of the green pea growing in the pod.  For these reasons the granary knows no final multiplication on the part of the despoiler.

The origin of the evil is in the kitchen-garden.  It is there that we ought to keep a watch on the misdeeds of the Bruchus, were it not for the fact that we are nearly always weaponless when it comes to fighting an insect.  Indestructible by reason of its numbers, its small size, and its cunning, the little creature laughs at the anger of man.  The gardener curses it, but the weevil is not disturbed; it imperturbably continues its trade of levying tribute.  Happily we have assistants more patient and more clear-sighted than ourselves.

During the first week of August, when the mature Bruchus begins to emerge, I notice a little Chalcidian, the protector of our peas.  In my rearing-cages it issues under my eyes in abundance from the peas infested by the grub of the weevil.  The female has a reddish head and thorax; the abdomen is black, with a long augur-like oviscapt.  The male, a little smaller, is black.  Both sexes have reddish claws and thread-like antennae.

In order to escape from the pea, the slayer of the weevil makes an opening in the centre of the circular trap-door which the grub of the weevil prepared in view of its future deliverance.  The slain has prepared the way for the slayer.  After this detail the rest may be divined.

When the preliminaries to the metamorphosis are completed, when the passage of escape is bored and furnished with its lid of superficial membrane, the female Chalcidian arrives in a busy mood.  She inspects the peas, still on the vine, and enclosed in their pods; she auscultates them with her antennae; she discovers, hidden under the general envelope, the weak points in the epidermic covering of the peas.  Then, applying her oviscapt, she thrusts it through the side of the pod and perforates the circular trap-door.