Pea weevil, Bruchus pisorum (L.)

The pea weevil (Bruchus pisorum) is a short (5 - 6 mm long), chunky, brownish beetle flecked with white, grey, and black. The white tip of the abdomen is marked with two black, oval spots. The white larvae have a brown head capsule and mouthparts. This insect is not strictly a weevil, as it does not have the typical weevil snout.

Life cycle
The adults overwinter with the peas primarily in storage, but also in the field. The pea weevil emerges about the time the peas are blooming, feeding on flowers (pollen and petal), leaves, or pods. The elongated, yellow eggs are laid on the outside of the pods. Although one to a dozen eggs are laid per pod, only one larva develops per pea. Hatching occurs in 1 to 3 weeks and the larva burrows through into the pea, maturing in 5 to 6 weeks. Infested peas "heat," aiding in the development of the larva. Pupation takes about 2 weeks, late in the summer. There is only one generation per year. Only green growing peas are attacked. The pea weevil cannot reproduce in stored grain, but the adults can remain concealed in grain for many months.

If there is a heavy infestation of pea weevils the infested peas are often reduced to shells. The larval stage of the weevil tunnel and develop within the pea. They may consume nearly the entire contents as they mature. Pupation occurs in the peas and adults emerge through a neat circular hole. They will only infest ripening peas so will not infest dry peas. Infested pea seeds can lose as much as 30 per cent of their weight. Weevil infested seed may germinate if the injury is confined to the cotyledon; but these seedlings are less able to compete with weeds and other pests.