A Guide to Grapevine Abnormalities in South Africa - P.G. GOUSSARD

Stem-borer wasps.

Fruit fly Once eggs have been laid in ripening berries, direct damage by the feeding activities of hatched, apodal larvae (bots) of the Mediterranean fruit fly is very characteristic – to be exact, typical, visually detectable brown-coloured tunnels are located under the skin (Photos 350 & 351). Since most of the larvae drown in the berry juice, very few of them reach the fully-grown stage when they leave the berries and pupate on the soil. In cases where fully-grown larvae are encountered (Photos 352 & 353), these are not to be confused with the larvae of vinegar-flies resulting from eggs being laid by such flies in berries that have been damaged by fruit flies and rotten organisms. Although fruit fly damage may occur in both table and wine grapes, the economic implications for the former are more severe.

PHOTO 336. Significantly less vigour, with no or delayed bud burst in this allocated bearer, resulting from feeding activities of stem-borer wasps ( tappieboorders ). In this instance they bore into pruning wounds, whereafter eggs are laid and further hollowing out actions are effected by the larvae.

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