it could be raspberry beetle according to my RHS book, below is the description:

Symptoms All cane fruits, inclucing raspberry, blackberry, loganberry and tayberry, are susceptable. The ripe fruits have dried up patches at the stalk end of the berries. When fully grown the larvae are up to 8mm long are creamy-white with pale brown markings on their upper surface. The grubs feed intiallt at the base of the berries but later feed on the inner core or plug. They are often seen crawling around the bowl after the fruits have been picked.
cause The larval stage of a small greyish brown beetle, Byturus tomentous. Eggs are laid on the flowers during early and mid-summer.
Control Timing control measures is important in order to control the newly-hatched grubs before extensive damage has occurred. On Raspberries, spray when the first pink fruits are seen; on logan berries and other hybrid berries, at 80% petal fall; and on blackberries, when the first flowers open. Spray with fenitrothion or derris at duck to minimise the risk to bees and other pollinating insects.

don't destroy the plants just treat them next year and hopefully you'll have a glut of berries.

Louise.