Caterpillars
The larvae of moths and butterflies, which chew holes in leaves, flowers and fruit and can strip a plant in days.
Also known as: Leaf-eating caterpillars, Loopers, Armyworms
Symptoms and identification
Ragged holes in leaves or leaves eaten down to the veins, chewed flower buds and bored fruit. Dark green or black droppings on leaves or the ground below are a clear sign. Some species roll or web leaves together to hide.
Causes
Moths and butterflies lay eggs on leaf undersides, and the larvae feed heavily as they grow. Outbreaks are common at the start of the monsoon and in spring, when new growth is abundant.
Organic treatment
Hand-pick caterpillars in the early morning or evening. Spray Bacillus thuringiensis (Bt), which affects only caterpillars, every 7 days while they are active, or use neem oil on young larvae.
Prevention
Inspect leaf undersides for egg clusters and crush them. Use fine insect netting over vegetables, and encourage birds and predatory wasps. Grow flowers that attract beneficial insects nearby.
Chemical treatment (use with care)
For severe attacks, use an insecticide labelled for caterpillars on that crop, following the label and the waiting period before harvest.