The Raspberry Crown Borer is a serious pest for raspberry growers. This pest infects the crowns and lower canes, often causing them to break off at ground level. Control by applying Diazinon in early October. The raspberry crown borer Bembecia marginata, a clear-winged moth, bores into and damages the lower cane or crown area of raspberries, blackberries, loganberries, and boysenberries, as well as wild thimbleberries and salmonberries.
Attacked canes become spindly, cane vigor is reduced, and canes break off at ground level.
The adult moth looks like a black and yellow wasp. It flies in the daytime and can be seen into October. Each female moth lives about a week and lays some 100 eggs singly on the undersides of the berry leaves. After about 30-60 days the eggs hatch into small caterpillars, which crawl down to the base of the canes and form individual overwintering cells. The majority of the eggs hatch in October.