As with adult moths, larvae are most active at night. One way of distinguishing the two species is that omnivorous looper larvae drop on a silken thread from leaves when disturbed while amorbia larvae do not. As the adult moth inside develops, its antennae, eyes and wings turn brown and can be seen through the pupal case. The pupal stage lasts 1 to 4 weeks. Pupae are usually found between two webbed leaves, or inside leaves that were rolled by mature larvae.
Wings are fawn-colored with a narrow black band running across the middle.
Undersides of the wings and body are white. Moths are strongly attracted to security lights or other bright light sources. Larval infestations are often concentrated near trees adjacent to light sources. Depending upon temperatures and humidity, the entire life cycle takes 9 to 11 weeks. There are five generations per year in the warmer southern parts of California.