Pea weevil

Bruchus pisorum

Symptoms: Once hatched, the larvae burrow directly from the eggs through to the pod wall and into the seed, creating a small, dark entry hole, about 0.2 mm in diameter. The larvae initially feed near the surface of the seed and then move into the centre of the seed to feed more extensively. Infested peas are 'heated' by the development of the larva. The fully-grown larva prepares an exit hole. It eats its way out towards the seed surface and chews a circular hole, about 3-5 mm in diameter, partly through the seed coat. A dark, circular window can be seen on the pea. The larva pupates behind this window. To determine if seeds are infested, larvae or pupae are easily extracted from seeds by soaking seeds in water overnight. Seeds are easily cracked open and larvae/pupae released. The water kills them but it avoids the possibility of crushing them beyond recognition. The new generation of adult beetles pushes the window open and leaves the seed, creating a 5-mm exit hole.