Hemlock looper moths are tan to grayish-brown in color and have a wingspan of approximately 1.25 inches. The female lays her tiny eggs on a variety of substrate throughout the forest from August to October. After overwintering in this stage the eggs hatch from late May to mid-June. The larvae feed initially on new foliage but quickly move to old foliage. They return to the new foliage only when the old foliage is depleted.
High populations can remove nearly all the new and old needles in a single season.
Adult moths are active from late summer through fall. This looper is a wasteful feeder, often nipping only a small part of a needle before moving to another. As these needles dry out they change color and along with the exposed twigs, result in a reddish-brown color characteristic of an infested stand. Often a mat of clipped needles collects under the tree. Characteristic notching of needles by the larvae.