Spotted Wing Drosophila

Spotted wing drosophila affects ripening fruit in the early stages of development. Photo courtesy of Martin Houser.

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The spotted wing drosophila (SWD) is a vinegar fly of East Asian origin that can cause damage to many fruit crops. Because these flies are only a few millimeters long and cannot fly very far, natural dispersion between states is unlikely. Human-assisted transportation is a more likely cause of the recent rapid spread.


  • Affects ripening fruit in the early stages of development.
  • Thrives at cooler temperatures.
  • May move from one crop to another as season progresses.
  • Populations can damage several different varieties of ripening fruit during a single growing season.

  • Damage first appears as near-microscopic scars on the fruit surface left by “stinging” females laying eggs.
  • SWD larvae hatch and begin feeding on the inside of fruit.
  • Fruit begins to collapse around the feeding site with soft depressions appearing on some fruits.
  • Mold and infestation by secondary pests may contribute to further damage.

  • SWD can be easily trapped in “McPhail”-type traps.
  • Other traps used to detect and control Tephritidae fruit flies also may be used to trap SWD.
  • Growers are encouraged to conduct their own detection activities and report their findings to their local Cooperative Extension Service office.

  • If SWD are detected, treat the crop with a registered insecticide. Check with your local Cooperative Extension Service office for insecticides registered for use in your area.
  • Rotate chemistries with different resistance management groups.
  • Evaluate your management program by monitoring for presence of flies with traps.
  • Sample fruit for larval infestation using fruit-dunk flotation method (See What Backyard Fruit Growers Need to Know About SWD).
  • Destroy leftover fruit on the plant or fruit that falls on the ground when practical to reduce the fly’s breeding site and food supply.
  • Consider post-harvest clean-up spray to reduce populations if SWD is captured post-harvest.
  • Check with your local Cooperative Extension Service office for insectides registered for use in your area.

4/28/2011 11:27:12 PM
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