Cabbage Looper | Diamond Back Moth
Cabbage loopers and diamond back moths damage cole crops.
Cabbage loopers (Trichoplusia ni) are grayish-brown moths with small silvery-white markings on the edge of the front pair of wings. Cabbage looper caterpillars get their name from the way they push the center of the body up into a large loop when they move. Full-grown larvae are green with a white stripe on each side and about 1 inch long.
Diamondback moth adults are small, grayish-brown moths with three diamonds on their body, which are more distinct on males than females. The larvae are green and feed under the leaf epidermis first and later on feed on the outer layer of the leaf.
Damage Caused By Cabbage Loopers and Diamond Back Moths
Caterpillars feed on leaves of brassicas (cabbage, broccoli, brussels sprouts, kale, collard, kohlrabi, etc.), spinach, and Swiss chard (leaving big holes on leaf surfaces) and continue feeding into the base of heads where they eventually reside. Pupa are found in loose white cocoons attached to the underside of the leaves.
Life Cycle of Cabbage Loopers and Diamond Back Moths
Cabbage loopers do not overwinter in the Midwest; they migrate from southern states in spring and summer. Pupates on the underside of the leaf in cocoons. There are two to three generations in the Midwest. Eggs are laid singly on the underside of the leaves or sometimes in small clusters.
Diamond back moths may overwinter as adults in protected areas, but this is not very common in the Midwest. They primarily migrate in large numbers as adults from southern states. They lay yellow eggs singly underside the leaves near veins.
Management of Cabbage Loopers and Diamond Back Moths
Gardeners: Caterpillars are frequently attacked by parasitic wasps. Green varieties of cabbage are less attractive to the moth.
- Place and grow plants under row covers over to prevent egg laying and feeding.
- Destroy crop residues after harvest.
- Plants can be sprayed with insecticides to manage caterpillars.
Commercial: The use of insecticides on cole crops will be needed if more than 10 percent of the plants are attacked in the seedbed or when plants are near harvest. Higher percentages of attack are acceptable on growing plants. Treat greens if 5% or more are infested.
Contact your county Extension office for current pesticide controls.