The relation between the pathogen Bacillus thuringiensis and the predator OHus albidepennis (Hem.: Anthocoridae) associated with the greasy cutworm Agrotis ypsilon (Lep.) has been investigated.The biology of the predator showed to be affected in terms of nymphal duration, rate of food consumption and egg production when the predator larvae were fed on treated eggs or neonate larvae of the host (A. ypsilon). The effect of B-exotoxin (thuringiensin) on the predator has been also demonstrated.