Spotted wing Drosophila

Drosophila suzukii

Drosophilidae: Diptera

Distribution: SWD is established or has been found in most fruit-growing states and provinces in eastern North America from QC and ON south to NC and west to WI, IL and KY.

Photos

Spotted wing Drosophila can be distinguished from other vinegar flies by spots on the wings of male flies, and by the ovipositor on female flies. First detected in the eastern United States in 2009-10, this small vinegar fly can lay eggs into grapes once the berries become soft after veraison. Unlike most vinegar flies, it can lay eggs into intact fruit, creating a risk of the white larvae (1-2 mm) being in berries at harvest time. With short generation time and high reproductive potential, populations can increase quickly, especially late in the season. Monitor for this fly using a vinegar-baited trap placed in the fruit zone and in the shade, checked weekly.

Crops Affected: berries, cherries, grapes

Damage

Female flies cut a slit and lay eggs in healthy fruit. The adult female SWD can lay hundreds of eggs in her lifetime of two to three weeks. Infested fruit do not show obvious symptoms of infestation at first, with only a small pinprick visible from the egglaying. Eggs hatch in 5-7 days and larval feeding on the flesh leads to discolored regions and eventually to collapse of tissues.

Management

Adults can be monitored using a trap made from a plastic cup containing a drowning solution and baited with one of a variety of attracts and hung in the plant canopy. A combination of yeast and sugar in water is highly attractive to adult SWD. Commercial lures are also available.