Garden Pests: Cabbage looper moth

This time of year we will start seeing these grayish brown moths around all brassica crops (broccoli, cauliflower, Brussels sprouts, collards, kale, mustard greens, turnip greens, radishes, turnips, rutabagas, and kohlrabi). They also feed on tomato leaves, spinach, cucumber, potato, and Swiss chard. They have small silvery white markings on the edge of their front pair of wings.

Young larvae (caterpillar) chew on the surface of the leaf while older larvae eat irregular holes. They like to feed on the most tender part of the plant which is the growing tips and can get into the developing cabbage or broccoli head. Once inside the heads they are not easily washed out at harvest. You will need to look for these at night. They are 1 ¼” long (3.2 cm) with a smooth green body with a white stripe along each side.

This moth typically goes through up to five generations per year (two to three in Canada, five in North Carolina, five to seven in California). They do not overwinter, as they do not tolerate prolonged cold weather, so the adults migrate from southern states in spring.

There are three variations commonly referred to cabbage worm:

The imported cabbage worm is a caterpillar in the butterfly family. It has fine, short fuzz and is bright green in color. The adult is the small white, a common butterfly.

The cabbage looper is a member of the moth family. The caterpillar is smooth and green with white stripes.

The diamondback moth is a member of the moth family. The caterpillar is smooth and solid green in color. When disturbed, it thrashes and drops off the plant. The newly-emerged larva is a leaf miner, entering the tissues of the leaf and consuming the parenchyma between the two outer layers of the leaf. Larger larvae make holes through the leaf, consuming all the tissue. The adult of the species is a small, elongated gray moth with whitish spots on the forewings that form two diamond shapes when the moth is at rest. The diamondback moth is primarily a tropical species, but is migratory, reaching temperate zones in most years.

Non-chemical control:
Parasitic wasps, Bt, row covers, destruction of crop residues after harvest.

You can also use Spinosad (derived through the fermentation of a naturally occurring organism).