Green with pale stripes, this caterpillar has legs at the front and back, but more in the middle―a peculiarity that gives it a characteristic humpback or looping crawl. Fully grown, the pests are about 1½ inches long.
Target: Cole crops, lettuce, celery, tomatoes, and various other vegetables and flowers.
Damage: Large, irregular holes are chewed in leaves. Holes are bored in tomatoes and in cabbage and lettuce heads. Seedlings may be killed.
Life cycle: Moths lay greenish white eggs singly on leaves. The caterpillars feed for a few weeks, then pupate on the plant; pupae may overwinter; or adults may migrate south. There are two to seven generations a year.
Notes: Wasps parasitize cabbage loopers, if you see eggs on caterpillars, leave to their fate. Also leave chalky white loopers alone―they’re infected with a virus. Since cabbage loopers feed first on outer leaves, you can often just pull the marred leaves from the heads of cabbage or lettuce and still get a good harvest.