Host Plants - The cabbage maggot feeds primarily on crucifers such as cabbage, cauliflower, broccoli, brussels sprouts, collards, kohlrabi, radish, and turnip. Beet, cress, and celery have also been infested. Damage - Cabbage maggots eat small fibrous roots and tunnel in stems and large fleshy roots. Tunnels where maggots have fed become brown and slimy, and organisms are likely to be introduced at these points. Plants attacked in the plant bed or soon after setting in the field fail to develop normally.
Cabbage first takes on a sickly gray-blue color.
Other infested crucifers may appear stunted or pale in color. If severe damage has been done, plants may wilt and die during the heat of the day. Infestations are difficult to detect in radishes and turnips because the tunneling of maggots in these large-rooted crops does not cause the foliage to wilt. Damage to these crops can be determined only by pulling some plants early and inspecting them. Cabbage maggots are usually most severe when the weather is cool and wet for a long period of time.