Distinctive green, white-lined larva, or caterpillar (Trichoplusia ni), of the owlet moth family (Noctuidae). Like other loopers, it moves in an inching motion. It is an economic pest of cabbages and associated crops, particularly in the U.S. and Europe. The adults, known as Ni moths, migrate considerable distances. They are mottled brown with a pale Y-shaped mark on each forewing. The typical adult wingspan is about 1 in. (25 mm).