Similar to the housefly. About 5-6 mm long, very hairy. Up to 4 generations/year. Nymph (maggots) up to 10 mm long, at the front of the mouth hook. At the rear end two dark breaths, which look like eyes.
Oviposition near root neck. Maggots damage by feeding on roots. Loss of taproot, wilting and dying off possible. Increased susceptibility to disease and wintering. Restricted water and nutrient supply
CONTROL BENCHMARK
In known infested regions, no early sowing dates.
If approved: Use insecticidal seed treatment to reduce heavy infestations relevant to yield.
Do not treat the cabbage fly with insecticidal sprays.
Maggots are not accessible to insecticide sprays at the root at 2 to 5 cm soil depth.
PREVENTION
Partial reduction of pupae (up to 5 cm in the soil) through soil cultivation in the rape seed after harvest.
Lower stand density usually means higher numbers of grubs / roots. Recommended minimum sowing rate 40-50 germinable grains/m².
Predatory beetles decimate eggs and maggots.
Larvae parasitisation by ichneumon flies and others.