This genus of 9 North American species includes The Hemlock Looper, Lambdina fiscellaria, a potentially destructive species of the eastern half of the U.S. as well as in the Pacific Northwest and into Alberta and British Columbia. Severe outbreaks can result in defoliation of the trees, leading to their death within a couple of years. They feed on many conifers including hemlock, fir, spruce, cedar, and pines, as well as hardwood trees such as maple, elm, birch, and cherry. Female moths deposit eggs in late summer and the eggs overwinter, hatching in late spring. The larvae feed on many needles, often eating only a small part before moving to another needle, but causing the death of all needles fed upon.
Foliar applications of contact insecticides will kill the larvae as they feed, and should be applied when larvae are first noted on the trees. The bacteria Bacillus thuringiensis is also effective but may require repeat treatments due to the prolonged emergence of the larvae from the overwintering eggs.