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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. Facts:
- 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.