The cabbage looper, Trichoplusia ni, is a serious pest of cruciferous plants such as cabbage, cauliflower, broccoli, and brussels sprouts. The adult cabbage looper is a gray, mottled moth with a characteristic white or silver "Y" mark on each forewing. The larva is a smooth, greenish caterpillar with thin white lines on its back and sides. It crawls in a looping motion. Cabbage loopers are present nearly the entire growing season. The cabbage looper also attacks carnations, nasturtium, lettuce, spinach, beets, parsley, potatoes, and tomatoes.
Damage: All cruciferous plants at all stages of growth are attacked by cabbage loopers, which are capable of completely defoliating plants. Larvae feed on the underside of developing leaves. Outer leaves become riddled with small irregular holes. If leaves are parted, masses of greenish-brown pellets of excrement are found at the bases of the leaves. Heads of cabbage and cauliflower are stunted.