Garden pest
Spotted wing drosophila
Soft, quickly-rotting ripe berries with tiny larvae inside. Pick often, chill fast, hang traps, exclude with fine netting.
Spotted wing drosophila is in its active season now — scout your plants this week.
How to identify spotted wing drosophila
A tiny tan fruit fly about an eighth of an inch long. The males carry a single dark spot near the tip of each wing, which is where the name comes from.
Unlike the common fruit flies that swarm overripe and rotting fruit, spotted-wing drosophila attacks intact, ripening fruit. The female has a saw-like ovipositor that cuts into sound berries to lay eggs, so the damage starts before the fruit ever looks spoiled.
Inside a soft, collapsing berry you'll find tiny white legless larvae. A berry that felt firm yesterday can go soft and leak within a day of infestation.
Attacks: Raspberries, Blueberries, Blackberries, Strawberries, Cherries
Life cycle: Adults lay eggs in ripening fruit; the larvae feed inside for a few days and the fruit collapses, then they pupate and a new generation emerges in as little as one to two weeks. Populations build fast through summer, so late-season fruit takes the worst hit.
Signs of spotted wing drosophila
What you actually see on the plant — usually before you spot the pest itself.
- Ripe berries that go soft, sunken, and leaky within a day
- Tiny white maggots inside otherwise sound-looking fruit
- Whole pickings collapsing or fermenting faster than normal
- Small egg-laying scars or 'breathing tubes' on the skin of firm fruit
Organic control, least-toxic first
Start at the top and only move down if you need to. Physical and cultural fixes come before any spray.
- Harvest often and completely, then chill fast
Pick every ripe berry every day or two and leave nothing on the plant to ripen further. Get the fruit into the refrigerator right away — cold quickly stops the larvae inside, buying you clean fruit and cutting the next generation.
- Remove and destroy overripe and dropped fruit
Fallen and overripe berries are the breeding factory. Collect them and seal them in a bag or solarize them — don't toss them loosely on the compost, where the larvae keep developing.
- Exclude the flies with fine netting
Fine mesh insect netting (fine enough to stop a tiny fruit fly) over a bush or a small planting keeps the egg-laying females off the ripening fruit. Put it on before the fruit starts to color.
- Hang traps to monitor, not to controlUse with care
Cups of apple cider vinegar (a red trap catches more) tell you when the flies have arrived so you can tighten harvest and sanitation. Traps track pressure — they won't clear an infestation on their own.
- Use spinosad only where pressure is high
Where the crop is being overwhelmed, a spinosad product labeled for the fruit and this pest can knock the adults back. Rotate modes of action, mind the pre-harvest interval, and follow the product label for rate and timing.
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One rule for any product you spray: follow the label. The label is the law, and it is the tested, safe rate for your plants — homemade mixes and dish-soap sprays are not, and can scorch foliage.
Prevent it next season
- Pick ripe fruit completely every day or two through the season — never let berries overripen on the plant
- Chill harvested fruit immediately to stop any larvae already inside
- Clean up dropped and cull fruit and destroy it rather than composting it loosely
- Net small plantings before the fruit begins to color
- Prune for an open canopy so fruit dries fast and is easier to pick clean
Questions about spotted wing drosophila
Why are my ripe berries suddenly soft with maggots inside?+
Spotted-wing drosophila. Unlike ordinary fruit flies, it lays eggs in intact ripening fruit, so the berries collapse within a day. Pick often, chill the fruit fast, destroy culls, and net the plants.
How is SWD different from a regular fruit fly?+
Common fruit flies only go after overripe or damaged fruit. SWD females have a saw-like ovipositor that cuts into sound, ripening berries to lay eggs, so they ruin fruit that still looks perfect.
Do vinegar traps get rid of spotted-wing drosophila?+
Traps are for monitoring, not control — they tell you the flies have arrived. The real control is frequent complete harvest, chilling fruit fast, sanitation, and exclusion netting, with a labeled spinosad only where pressure is high.
Plan a garden that fights back
Healthy, well-spaced plants shrug off pests that flatten a crowded bed. PlotToTable sizes your beds, spaces every crop, and flags the pests that hit what you grow.