Flea Beetles
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 18°C and 32°C, in dry air below 55%.
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
Flea beetles (Phyllotreta species) are tiny shiny beetles that jump like fleas when disturbed. They shot-hole the leaves of radish, rocket, turnip, cabbage seedlings and other brassicas, and they are at their worst in hot, dry weather on young plants.
Symptoms
Dozens of small round holes peppering the leaves, heaviest on the youngest growth. Seedlings can be killed outright or checked so badly they never catch up. The beetles scatter with an audible flick when you lean over the row.
Organic Treatment
Cover seedlings with fine mesh from the day of sowing. Keep the bed damp — flea beetles hate humidity, and overhead watering in the morning noticeably reduces feeding. A sticky yellow board dragged along the row collects large numbers.
Chemical Treatment
Pyrethrum-based contact sprays applied in the evening give short-lived knockdown. They also kill beneficial insects, so reserve them for a seedling crop about to be lost.
Prevention
Sow into warm soil so seedlings grow through the vulnerable stage fast, water generously in dry spells, use mesh on every brassica sowing, and clear plant debris in autumn where the adults overwinter.
Crops at risk
Related problems
Flea Beetles 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.