Egg - Virtually nonexistent in the South, the eggs of these
aphids are minute, ovate, and black and are laid only in the
fall. Nymph - The wingless nymphs resemble the adults in color
and shape but are smaller. Host Plants - The cabbage aphid feeds
primarily on broccoli, brussels sprouts, cabbage, cauliflower,
collards, kale, and radish. Mustard is rarely infested. The
turnip aphid typically infests mustard, radish, shepherdspurse,
turnip, and watercress. It also injures other crucifers,
particularly in their seedling stage. Damage - Aphids cluster on
the underside of leaves and suck sap causing infested foliage to
curl, wilt, or become distorted. Some infested plants are soon
killed; others grow slowly, are stunted, and produce small
unmarketable heads. Life History - In North Carolina, cabbage
and turnip aphids continue to feed and breed at reduced rates
throughout the winter. Collards are an important overwintering
host plant. As warm weather returns, aphid activity increases.
Wingless female adults produc