Cherry: Spotted wing Drosophila (SWD)

Photo by: W. Hoashi-Erhardt
Use IPM (Integrated Pest Management) for successful plant problem management.

Biology
Spotted wing Drosophila (SWD) resembles other Drosophila species (fruit flies or vinegar flies) in appearance, but unlike other members of the family which attack only overripe, damaged or decaying fruit, SWD attacks healthy fruit as it ripens on the plant. Adult SWD flies are about 1/8 inch long, with red eyes and a yellow-brown body. Darker bands may be visible on the abdomen. Male flies have a distinctive dark spot on the leading edge of the wing near the tip. SWD is the only fruit fly species in our area with this spotted wing, making identification of males relatively simple. Females lack the spotted wing, but have a large, sawlike egg-laying organ called an ovipositor at the tip of their abdomen. It is used to deposit eggs in fruit (oviposition). The eggs are laid beneath the surface of ripening fruit as it begins to soften and show color (from light straw color in sweet cherry), continuing through to harvest. Scars left by oviposition may appear as indented, soft spots on the fruit surface. Small white- or cream-colored larvae hatch within a few days and feed in the fruit, causing the fruit to soften and collapse around the feeding site. Further damage may be caused by secondary pathogens (fungi and bacteria) which attack the damaged fruit. At maturity, the larvae may be up to 1/8 inch long. They may pupate inside or outside the fruit. The length of the life cycle depends on temperature, with adults most active at cool temperatures (around 68 degrees F). Most soft-skinned fruits are vulnerable to attack by SWD, including peach, plum, cherry, grapes (table and wine), strawberry, blueberry, and cane fruits. It has also been found in Asian pear, fig, and hardy kiwi. See SWD under Common Insects for an additional image of the larval stage.

Management Options

Select Non-chemical Management Options as Your First Choice!!
Revision Date:5/20/2014
Chemical applications are effective against ADULTS ONLY and will not control SWD eggs, larvae, or pupae in fruits. CHERRY must be listed on the pesticide label. Monitoring for the presence of SWD is necessary to determine correct application timing, as these products are strictly protective. Good spray coverage of the foliage and ripening fruit is essential to prevent oviposition by the females. Since SWD are active for several months, multiple applications may be needed. To help prevent development of SWD resistance to pesticides, DO NOT make multiple applications of the same active ingredient. Alternate between different active ingredients, remembering to observe the pre-harvest interval (PHI) on the product label. Most of the products listed are expected to have residual activity against SWD for approximately 7-10 days. Products containing pyrethrins have little to no residual activity, but because of their shorter PHI they may be used to protect fruit closer to the harvest date. CAUTION: These pesticides are toxic to bees. To reduce risk to pollinating bees, make pesticide applications in the evening after bees are done working for the day. Do not apply on or near flowering plants. Homeowners should not make foliar applications to trees over 10 ft. tall. Consult a commercial pesticide applicator for treatment of trees over 10 ft. tall.

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Hortsense web site created by Carrie Foss, Pesticide Education, and Art Antonelli, Extension Entomology, WSU Puyallup
Pesticide information review provided by Catherine Daniels, Washington State Pest Management Resource Service
Database programs developed for Hortsense by Kathleen Duncan, Computer Resources, WSU Pullman
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