The Cabbage Looper is a serious pest of the cabbage, cauliflower, broccoli, and brussels sprout plants. It can be seen in all parts of the Pacific Northwest.
The adult cabbage looper is a grayish, mottled moth with a silver marking on each wing that is in the shape of a Y. The caterpillar is a smooth, green-colored caterpillar with thin white lines on its back and sides. It has no middle legs and moves in a looping motion. Cabbage loopers are present throughout the entire growing season. The cabbage looper will also attack carnations, nasturtiums, lettuce, cole, spinach, beets, carrot tops, potatoes, and tomatoes.
The plants that are attacked by cabbage loopers can become completely defoliated. Larvae feed on the underside of developing leaves. The outer leaves become riddled with small irregular holes. If you look close, you will see masses of greenish-brown pellets (droppings) at the bases of the leaves and the heads of cabbage and cauliflower will become stunted.
The cabbage looper overwinters on plant debris. The moth emerges in spring and is active at night. It lays round pale yellow eggs on the upper and lower surface of the leaves. The eggs hatch in 3 to10 days. Larvae are about 4 cm long and are green with pale stripes down their back. They loop their bodies as they crawl. The caterpillars feed on plants for 3 to 4 weeks.