Rove beetles and root maggots
UMass notes that ground and rove beetles eat cabbage maggot eggs, larvae and pupae and can cause high mortality. One rove beetle, Aleochara bilineata, also parasitises the pupae: its adults eat the eggs and larvae, and its larvae develop inside the pupae. In Alberta canola its emergence began shortly after the flies started laying. UMass warns these soil beetles are susceptible to insecticides, so avoid broadcast soil treatments where root maggots are the problem.
Before you act
Slender beetles with wing cases so short that most of the abdomen is bare, so they look more like an earwig than a beetle. Most hunt tiny prey in compost, leaf litter and topsoil. One member of the family, Dalotia coriaria, is sold as a greenhouse biocontrol; the rest arrive on their own. How to recognise it, what it is confused with and how to keep it around are on the full Rove beetles profile.
Other controls for root maggots
- Steinernema feltiaeNematode · 100,000–125,000 infective juveniles per transplant (UMass, from trials)
- Ground beetlesWild predator · Nothing to release — give them cover