The cabbage aphid is greenish white.
Large populations cause cupping and curling of the leaves and prevent head formation.
The turnip aphid is greenish and sucks juices the undersides of leaves. This causes the leaves to yellow and curl. It injures brassica by eating leaves. Sprays of Bacillus thuringiensis may be used on Broccoli, Brussels Sprouts, Cabbage, Cauliflower, Collards, Kale, Mustard Greens and Turnip Greens. They begin feeding in late May to early June.