Braconid wasps for cross-striped cabbageworm
The braconid Cotesia orobenae parasitises cross-striped cabbageworm. In a Missouri organic cabbage trial, its parasitism rose significantly on the brassica trap crop when sweet alyssum and buckwheat were planted alongside (Shrestha et al. 2019). It is not sold. If a spray is needed, Bt kurstaki is the caterpillar spray UC IPM rates low in toxicity to parasites.
Before you act
Small parasitic wasps (the common Cotesia species are only 2–3 mm long) whose larvae develop inside a caterpillar or an aphid and kill it. The white, rice-grain cocoons standing up on the back of a hornworm are theirs, and a hornworm carrying them should be left on the plant. How to recognise it, what it is confused with and how to keep it around are on the full Braconid wasps profile.
Other controls for cross-striped cabbageworm
- Bacillus thuringiensis kurstakiMicrobial insecticide · Label rate — DiPel DF lists cross-striped cabbageworm, 0.5–2 lb per acre on leafy brassicas; the Thuricide home label does not list it
- Trichogramma spp.Egg parasitoid wasp · One card of about 100,000 T. brassicae per acre per week (UMass)