Cabbage loopers are destructive green caterpillars that grow to be 1½ inches long. In addition to their tell-tale white stripes, an infestation can be identified by the presence of tiny green eggs on the surface of leaves. The eggs are laid by the brownish adult moths that spread the pest from plant to plant.
Blame the Chew Marks on These Guys
If your cabbage or broccoli plants look a little raggedy, it's probably the fault of cabbage loopers. As young larvae, they can feed for 2 to 4 weeks on your vegetable plants, causing considerable damage. Their plants of choice are members of the cabbage family - cabbage, broccoli, Brussels sprouts, cauliflower, kale, and turnip), but they'll also feed on lettuce, spinach, parsley, and tomatoes, among others. An infestation can last from early spring, when the eggs have been laid, to late fall when the next generation of pupae rest for the winter.
The edges of foliage and flower buds usually looked chewed after the cabbage loopers begin to feed. There might also be irregular round holes through the leaves.
Check your plants for the presence of cabbage loopers before treating. Look for eggs and larvae on the underside of the leaves - start your search in the area of the plant where you see damage. To control a current infestation, use Ortho® Flower, Fruit & Vegetable Insect Killer. Always read and follow the label directions.