The western grape rootworm (Bromius obscurus) is a widespread pest of grapevines in Europe and California, but damage to grapes in B.C. was not reported until recently when an outbreak occurred in the Kelowna area.
Fully grown larvae are C-shaped white grubs about 7 mm long with yellowish brown heads and dark mouthparts. Adult beetles are about 4 mm long and somewhat hairy with nearly black heads and dark bodies.
Adults, which are all females, start emerging in May and feed on the expanding leaves of grapes, causing long slit-like holes. Larvae initially feed on root hairs before tunnelling into the roots of grapevines.
Feeding by western grape rootworm larvae is known to cause the death of vines in California due to direct damage to the roots and entry of secondary pathogens.
B.C. Ministry of Agriculture fact sheet: PEST ALERT: Western Grape Rootworm (Bromius obscurus) (PDF)
