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Spotted Wing Drosophila (SWD)

Program Contact: Don McMoran, County Director
(360) 395-2357 •

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.

SWD trap in Strawberries
SWD trap in Strawberries

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