Caterpillars
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 33°C.
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
Caterpillars — the larvae of moths and butterflies such as cabbage worms, hornworms and loopers — chew foliage and fruit of vegetables and ornamentals through the warm season.
Symptoms
Ragged holes and chewed leaf margins, stripped stems, dark green or black droppings (frass), and tunnelled or bored fruit; large green or striped larvae present.
Organic Treatment
Hand-pick larvae, spray Bacillus thuringiensis (Bt) or spinosad, and protect crops with floating row cover. Encourage birds and parasitic wasps.
Chemical Treatment
Spinosad or targeted insecticides; reserve broad-spectrum products for heavy infestations to spare pollinators and predators.
Prevention
Cover susceptible crops with insect netting, remove eggs on leaf undersides, rotate brassicas, and attract beneficial insects with flowers.
Crops at risk
Related problems
Caterpillars 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.