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How to identify it
- Adults are only about 1/12 to 1/8 inch long, yellowish brown, with bright red eyes and dark bands across the abdomen.[2][1]
- Males are the easiest to recognize: each clear wing has a dark spot near the tip.[1][2]
- Females have unspotted wings and a large, saw-toothed egg-laying tube, but seeing those teeth takes strong magnification.[2][1]
- Larvae are tiny white maggots, about 1/8 inch when full grown, with no legs or visible head; one to several may feed inside a single berry.[2][1]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Common fruit fly (vinegar fly) | Looks very similar, but common vinegar flies mainly lay eggs in rotting, fermenting or already damaged fruit, while spotted-wing drosophila attacks sound, ripening fruit.[1] |
| Western cherry fruit fly | A larger fly, about 3/16 inch long, with dark bands across the wings instead of a single spot at each wing tip.[1] |
Where it lives
Native to Asia; first found damaging fruit in California in 2008 and now present in most of the main fruit-growing regions of the United States.[1][2]
Biology and life cycle
The life cycle can take as little as about a week in warm weather, and there can be up to 10 generations a year.[2][1]
Females can begin laying eggs one day after they emerge, so numbers build quickly once flies show up.[2]
Each egg-laying puncture, or sting, holds one to three eggs; mature larvae leave the fruit, partly or completely, to pupate.[1][2]
In Minnesota flies appear in late June or early July and peak in August and September; most arrive from farther south.[2]
In California's inland valleys they are most active in spring and fall, when highs run between 60 and 80 degrees F; heat above 86 degrees F slows them.[1]
It survives winter as an adult fly.[2]
Damage and signs
- Larvae feed inside the fruit, turning the flesh brown and soft with sunken spots that may leak juice on cherries and blueberries.[1][2]
- Damage often isn't noticed until harvest; berries that looked fine can turn soft and wormy a day or two later on the counter.[1][2]
- Infested fruit often smells sour or fermented, and the wounds let rot fungi, bacteria and other insects move in.[2][1]
- Raspberries are especially susceptible; it also attacks blackberries, blueberries, strawberries, grapes, plums and cherries.[1][2]
- It doesn't attack healthy apples, pears or cherry tomatoes, though it can infest them once they are damaged.[2]
Health risk
No known health risk: eating fruit with spotted-wing drosophila in it is not known to harm people. The damage is to the fruit crop.[2]
Control
Keep them out
Cover berries or small trees with very fine insect netting before fruit begins to ripen, sealing the edges so flies can't get under it.[1][2]
Sanitation
Pick ripe fruit often, and gather fallen or infested fruit into a sealed plastic bag for the trash.[1][2]
Don't compost or bury infested fruit; composting is unreliable, and the flies can survive burial up to 18 inches deep.[2][1]
Traps and physical control
Hang a vinegar trap in the shade near your fruit before it starts to ripen; a lidded quart container with small holes and an inch of plain apple cider vinegar works.[1][2]
Check the trap weekly for small flies with dark wing-tip spots, and check ripening fruit for tiny stings that leak juice when gently squeezed.[1]
Pesticides
Sprays only kill adults before they lay eggs and won't help fruit that is already infested, so confirm the pest first and spray as fruit begins to color.[1][2]
Extension names spinosad as effective with relatively low environmental impact; carbaryl, malathion and pyrethrin also kill adults, but malathion is very toxic to bees.[1][2]
Spray in the evening to protect pollinators, rotate insecticide classes, and observe the label's waiting period before harvest.[2][1]
Common questions
- Why are my raspberries turning mushy with tiny worms inside?
- Spotted-wing drosophila is a likely cause: the females lay eggs in ripening berries, and small white maggots soften the fruit from inside.[1][2]
- Is it safe to eat berries that might have spotted-wing drosophila?
- There is no known health risk from eating them. Refrigerating fruit you suspect is infested slows or stops larval growth.[2]
- Will a vinegar trap get rid of spotted-wing drosophila?
- No. Traps tell you the flies are present and when to act, but trapping hasn't been shown to reduce backyard populations.[1]
Sources
- University of California Statewide IPM Program, “Spotted-Wing Drosophila (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/spotted-wing-drosophila/ (accessed 2026-10-06)
- University of Minnesota Extension, “Spotted Wing Drosophila (Yard and Garden Insects).” extension.umn.edu/garden-and-home/yard-and-garden/yard-and-garden-insects/spotted-wing-drosophila (accessed 2026-10-06)
- iNaturalist, “Drosophila suzukii taxon page (order and family).” www.inaturalist.org/taxa/311582 (accessed 2026-10-06)