BeneficialSod webworms
Bt (kurstaki) for sod webworms
Bacillus thuringiensis kurstaki · microbial insecticide
Against sod webworms
UC IPM lists Bt kurstaki as a sod webworm treatment, but warns that it breaks down quickly in sunlight, washes off the leaves and does not work on late-instar larvae. Apply it in the evening, time it to the young larvae 2–3 weeks after the moth flight peaks (UMass), and do not irrigate for 2 days after treating (UC IPM).
RateLabel rate — DiPel DF lists sod webworm (Crambus spp.), turf 0.5–2 lb per acre
TimingOn young larvae, 2–3 weeks after the peak moth flight; apply in the evening
macro · bt (kurstaki) on sod webworms
The pestSod webwormsCrambidae (Crambus, Parapediasia and relatives)Small ragged brown patches; grass blades notched and clippedFull 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 sod webworms
- Steinernema carpocapsaeNematode · 25 million per 1,000 ft² (about 270,000 /m²) (UC IPM)
- Braconid waspsWild parasitoid · wild, attract it
- Rove beetlesWild predator · wild, attract it