Spotted Wing Drosophila Update

Posted: July 5, 2012

Spotted wing drosophila (SWD) is present on a number of farms in southeastern Pennsylvania and central Maryland. Larvae have been detected in cherries at the tail end of harvest and summer raspberries, blueberries, blackberries, and primocane-fruiting raspberries where lateral canes emerged from pruning stubs.

Kathy Demchak ( and Dave Biddinger (, Penn State; and Bryan Butler (, University of Maryland

This is a concern -- the small amount of fruit on these lateral canes is low on the plant and often hidden in foliage. This fruit should either be harvested or these canes should be removed with the fruit attached. Otherwise, SWD will multiply on the unharvested berries with high numbers of flies present and ready to attack the main primocane crop when it begins to ripen. Adult males are being found in traps, but in low numbers and in almost every case, larvae in fruit were noticed first. An article on management follows.