BeneficialCabbage worms
Bt (kurstaki) for cabbage worms
Bacillus thuringiensis kurstaki · microbial insecticide
Against cabbage worms
UF/IFAS says imported cabbageworms are readily killed by Bt, and Wisconsin Extension calls it very effective against small ones. Spray both leaf surfaces, because the caterpillars rest along the midrib underneath. UC IPM rates Bt low-toxicity to predators and parasites, so the Cotesia wasps that parasitise cabbageworms survive the spray.
RateLabel rate — Thuricide 1–3 tsp per gallon for imported cabbageworm on broccoli, Brussels sprouts, cabbage, cauliflower, collards and kale; DiPel DF 0.5–2 lb per acre
TimingAt the first sign of feeding, while caterpillars are small and before they enter the heads; repeat weekly as needed and after heavy rain
macro · bt (kurstaki) on cabbage worms
The pestCabbage wormsPieris rapaeLarge ragged holes in brassica leaves, caterpillars and green frass in the headsFull pest profile →Before you order
A bacterium sprayed on leaves. Caterpillars that eat it stop feeding and die within a few days. It works only on the larvae of moths and butterflies, and has little or no effect on bees, lady beetles, lacewings or parasitic wasps. How it works, how to tell it has established and the supplier list are on the full Bacillus thuringiensis kurstaki profile.
Other controls for cabbage worms
- Braconid waspsWild parasitoid · Nothing to release — leave parasitised caterpillars and cocoon clusters on the plant
- Trichogramma spp.Egg parasitoid wasp · One card of about 100,000 T. brassicae per acre per week, for about 4 weeks or through the crop (UMass); 1–2 /ft² in gardens
- Tachinid fliesWild parasitoid · wild, attract it
- Paper waspsWild predator (stings) · Wild — tolerate nests away from doors and paths