Cabbage Looper
The cabbage looper is a medium-sized moth in the family Noctuidae whose larvae are a serious and common pest of brassica crops. In upstate New York and Zone 6b, adults do not overwinter locally but migrate north from southern populations each season, typically arriving by midsummer. Gardeners growing cabbage, broccoli, kale, cauliflower, Brussels sprouts, or bok choy should plan on seeing this pest and scout for it regularly once warm weather sets in.
The larva earns its name from the way it moves. It lacks the middle prolegs that most caterpillars have, so it pulls its rear end forward and arches its body into a distinct loop with each step, much like an inchworm. Adults are brownish-gray moths marked with a small silver figure-8 on each forewing. Females lay dome-shaped eggs singly on leaf surfaces, and larvae hatch within a few days. Multiple overlapping generations can develop through the growing season, meaning pressure tends to build as summer progresses into fall.
A primary defoliating pest of brassica crops, with larvae capable of causing rapid and significant leaf loss through summer and fall.
Ragged, irregular holes in outer and wrapper leaves caused by pale green caterpillars that arch their bodies in a looping motion when moving. Heavy populations consume leaf tissue down to the midrib and bore into forming heads.
Apply Bacillus thuringiensis var. kurstaki (Bt) at the first sign of feeding, targeting larvae while they are small. Reapply every 5–7 days during wet weather. Use floating row cover to exclude egg-laying adults. Hand-pick caterpillars on small plantings. Parasitic wasps are effective natural controls; avoid broad-spectrum insecticides that kill them.