Our Bruchus is not a sedentary inhabitant of the granaries: she needs
the open air, the sunshine, the freedom of the fields. Very frugal on
her own behalf, she absolutely disdains the hardness of the legumen;
all that her slender snout requires is a few honeyed mouthfuls sipped
from the flowers. The larva, on the other hand, demands the soft bread
of the green pea still growing inside the pod. For these reasons, the
storehouse knows no further multiplication on the part of the ravager
introduced at the beginning.
The origin of the mischief lies out of doors. It is here more than
elsewhere that we ought to keep a watch on the Weevil’s misdeeds, were
it not that we are nearly always unarmed when it comes to fighting
against insects. Indestructible because of their numbers, their small
size, their sly cunning, the little creatures laugh at man’s anger. The
gardener fumes and curses; the Weevil remains unconcerned:
imperturbably she continues to levy her tithe.
Fortunately, we have assistants, more patient and more clear-sighted
than ourselves. In the first week of August, when the adult Bruchus is
beginning to move away, I make the acquaintance of a little Chalcis,
the protector of our peas. In my rearing-jars a number of her comes out
of the Weevil’s home before my eyes. The female has a red head and
thorax and a black abdomen, with a long boring-tool. The male, a little
smaller, is clad in black. Both sexes have dull-red legs and
thread-like antennæ.
In order to leave the pea, the exterminator of the Bruchus opens
herself a window in the centre of the disk which the Weevil’s grub has
bored in the skin with a view to its future deliverance. The devoured
has prepared the way out for the devourer. This detail enables us to
guess the rest.
When the preliminaries of the metamorphosis are finished, when the
exit-hole is bored, furnished with its lid, a surface cuticle, the
Chalcis comes bustling along. She inspects the peas, still on the
plant, in their pods; she tries them with her antennæ; she discovers,
hidden under the general outer wrapper of the pod, the weak points in
the ceiling formed by the skin. Then, raising her sounding-rod, she
thrusts it through the pod and pierces the thin lid. However deeply
secreted in the centre of the pea, the Weevil, whether larva or nymph,
is reached by the long implement. It receives an egg in its tender
flesh; and the trick is done. Without any chance of defence, for it is
by now either a torpid grub or else a nymph, the corpulent infant will
be drained to the skin.
What a pity that we are not able at will to promote the multiplication
of this zealous exterminator! Alas, our agricultural auxiliaries have
us in a disappointing vicious circle: if we wish to obtain the
assistance of large numbers of the Chalcids that bore holes in peas, we
must first have large numbers of Pea-weevils!
CHAPTER XIII
THE HARICOT-WEEVIL
Public-domain text, read in full here on John Shaqi.
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