Spotted Wing Drosophila
Risk near you, next 48h
See whether your local forecast favours this disease right now.
When it strikes
Treat, then re-check in 5–7 days
Pick off the worst material, apply the organic option below, and look again after five to seven days. If the spread continued, escalate rather than repeating the same treatment.
Carried by insects
An insect moves it plant to plant, so controlling the carrier matters as much as treating the symptom. Check for the vector before assuming the plants infected each other directly.
Safe to compost
No pathogen carries over on this material, so it can go on an ordinary heap with the rest of the garden waste.
When and where to look
Scout the planting while temperatures hold between 15°C and 30°C, with humidity above 70%.
Rule these out first
Same category, and at least one host crop in common — so they are genuinely confusable in the same part of the garden.
The signs that lead here
Full problem lists for these crops
About
Unlike ordinary fruit flies, spotted wing drosophila (Drosophila suzukii) has a serrated ovipositor that cuts into sound, ripening fruit rather than waiting for it to spoil. Since arriving in Europe in 2008 it has become the main pest of cherries, raspberries, blueberries and late strawberries.
Symptoms
Fruit softens and collapses within a day or two of looking perfect, with a tiny puncture scar on the skin. Cut it open and there are small white maggots inside. Whole pickings of raspberries turn to mush overnight.
Organic Treatment
Pick every ripe fruit every single day and remove all windfalls and over-ripe fruit from the ground — leaving them is what builds the population. Bag or freeze infested fruit rather than composting it. Fine 0.8 mm mesh over the whole plant works if fitted before ripening.
Chemical Treatment
Approved insecticides exist for commercial growers but have short harvest intervals that make them impractical when you are picking daily. Cultural control is the realistic garden answer.
Prevention
Grow early varieties that ripen before populations peak, prune for an open, airy canopy the flies dislike, hang vinegar-and-wine traps to monitor arrival, and keep the fruit area rigorously clear of fallen fruit.
Crops at risk
Related problems
Spotted Wing Drosophila risk by location
Each location has a month-by-month profile computed from the weather archive: how many hours a year actually meet this disease’s thresholds.