Bacteria were isolated from dead cabbage root fly larvae that had been exposed to cabbage root fly-suppressive soil amended with black soldier fly frass and their insecticidal activity was assessed. In laboratory bioassays, larvae were allowed to feed on swede slices treated with bacterial suspensions. The capacity of a Pseudomonas isolate to control cabbage root fly larvae was subsequently tested in the greenhouse. The isolate was applied to soil at 10^10, 10^9 and 10^8 CFU/kg and Brussels sprouts plants were grown in treated soil for 5 weeks before being infested with cabbage root fly larvae.