After overwintering as pupae in the soil, the flies emerge in spring, feed on nectar, and lay eggs close to plants of the genus Brassica.

They hatch into white maggots after about six days and the larvae feed for about three weeks on the roots and stems of the cabbage plants.

After this, the larvae are typically 0.9 to 1 cm in length and form reddish-brown pupae which hatch into adult flies after around 20 days.

[6] The first sign of the presence of the larvae is a delay in plant growth accompanied by the withering of leaves which develop a bluish tinge.

The larvae are found on cabbage, turnip, swede, radish, and other cruciferous crops.