Spotted Wing Drosophila

Program Contact: Michael R. Bush, Extension Entomologist
(509) 574-1600 • bushm@wsu.edu

In 2010, our WSU Plant & Pest Diagnostic eNetwork documented the Spotted Wing Drosophila (SWD), Drosophila suzukii, on the western side of Washington State. This pest was first reported in California in 2008 and has rapidly expanded its distribution along the Pacific Coast. In 2009, SWD was detected in the Willamette Valley and in Hood River, Oregon. This insect has been documented as a pest in soft-skinned tree fruits, and berries.

If you ever took any genetics courses, you might remember using Drosophila, or vinegar flies, in laboratory studies because these flies undergo multiple generations in one semester. There are Drosophila species native to Washington, but this species has an ovipositor that allows the female fly to puncture and lay eggs in undamaged fruit. As such, this pest could create problems for our agricultural industries as well as home gardeners.

WSU Extension in cooperation with multiple cooperators will be monitoring for SWD throughout Eastern Washington. SWD response teams and networks are in place. These networks will provide producers with management information to eradicate or contain SWD should it be trapped. Survey data has determined SWD can survive the temperature extremes experienced in the Yakima Valley. Anyone who traps or captures tiny (2-3 mm long) SWD flies, that look like vinegar flies but have spotted wings, are encouraged to bring them into our office for identification. Anyone who encounters tiny larvae in unbroken, soft skinned fruit including peaches, cherries, plums, raspberries, strawberries, blueberries, etc., are encouraged to bring these into our office as well.

Any finds or reports of SWD will be specific to geography and client confidentiality strictly maintained. The success of our response teams and the network will rely on early detection of this pest.