Caterpillars
This problem spreads through handling, insects or soil rather than the weather, so there is no live forecast risk — focus on prevention below.
When it strikes
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.