WSU Whatcom County Extension

SWD for Homeowners

WSU Whatcom County Extension                         

Spotted Wing Drosophila
Bev Gerdeman

Spotted Wing Drosophila (SWD)

Information for Homeowners


The spotted wing Drosophila (SWD), Drosophila suzukii (Matsumura) is a pest of soft fruit native to Asia, but was found in California starting in 2008, and in Washington and Oregon in 2009. Most Drosophila species, collectively known as vinegar flies, are attracted to overripe and rotting fruit for ovipositing sites, but SWD females have saw-like ovipositors which they use to lay eggs in ripening fruit, still on the plant.

Fruits targeted by this pest include strawberry, raspberry, blueberry, plum, peach, cherry, and grape. Damage is seen initially as tiny scar on the skin of the fruit, and then the skin collapses and may become moldy in the area where the egg was laid and the larva is developing. The larvae will feed inside the fruit for 5-7 days. Adult females can lay up to 350 eggs in a lifetime.

A research team, including scientists from California, Oregon, Washington and British Columbia are collaborating to understand the lifecycle of this pest as well as monitoring and management techniques.



Oregon State University has released several informative publications and videos for home gardeners including information on identification, monitoring and control. Find publications and videos for home gardeners on SWD here:

"Friends and Foes" article

SWD Information for Commercial Growers

Click on image to see it larger:

Life Cycle - click to see larger

Sex Combs - click to see larger

Oviposition in Strawberry - click to see larger

Eggs on and below surface - click to see larger

SWD Egg and Fly on Blueberry - click to see larger

Spiracles - click to see larger

Instar Larva - click to see larger

SWD Pupae - click to see larger

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WSU Whatcom County Extension • 1000 N. Forest St., Bellingham, WA 98225 • (360) 778-5800 •