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. All cruciferous plants and 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. The cabbage looper overwinters in a cocoon on plant debris. The moth emerges in spring and is active at night. It lays round, pale yellow eggs on the upper surface of the leaves.