About a dozen different species of these destructive moths occur in North America and are common throughout the continent, feeding on many different ornamental and forest trees including conifers, oak, ash, poplar, and fruit trees. Heavy infestations are capable of completely defoliating large trees. Egg masses deposited on the bark of the tree overwinter with larvae hatching in mid to late spring, coinciding with bud break on the host tree. Adult moths will be present during the summer months and there usually is a single generation each year.
The use of chemical sprays is often necessary to kill the larvae, including both synthetic insecticides as well as natural materials such as Bacillus thuringiensis. Sprays should be directed onto the larvae when first noticed on the foliage. A few larvae only on a tree will not cause significant damage and an insecticide treatment may not be warranted.