cabbage looper, moth larva, Trichoplusia ni, that feeds by night on the leaves of cabbage and related plants and is a serious agricultural pest. Like the inchworms (of another moth family), cabbage loopers lack walking appendages in the middle of the body and progress by drawing the rear end up to the front end and then straightening. A cabbage looper has a smooth green body with a white stripe along each side and reaches a length of 11/4 in. (3.2 cm). It pupates in a cocoon on the underside of a leaf. The adult moth is brown with a white spot on each wing. Cabbage loopers are classified in the phylum Arthropoda, class Insecta, order Lepidoptera, family Noctuidae.