Gypsy Moth (Lymantria dispar)

U.S. Department of Agriculture, Forest Service. 1979. A guide to common insects and diseases of forest trees in the northeastern United States. Northeast. Area State and Private Forestry, Forest Insect and Disease Management., Broomall, PA. p. 123, illus.(USDA Forest Service, Northeast Area State and Private Forestry Publication. NA-FR-4)

The gypsy moth is a defoliator primarily of hardwood trees, especially oak, although after the larvae are half-grown they will attack conifers. They usually do not infest ash, black walnut, catalpa, and yellow-poplar.

The range of this introduced pest is primarily the northeastern United States, from Maine south to New Jersey and west to western Pennsylvania. However, limited infestations have occurred in Lower Michigan and Wisconsin. Male moths have been reported as far west as Missouri.

The eggs hatch in late April or early May, with the larvae completing feeding in late June or early July. Older larvae may be recognized by the five pairs of blue spots and six pairs of red spots along the back. After feeding, the larvae pupate and emerge as adult moths in about 2 weeks. Shortly after the female emerges, she mates and begins laying eggs on trees, rocks, or other nearby objects. The female, too heavy with eggs to fly, deposits buff-colored masses of 100 to 1,000 eggs. The current year's egg masses can be found from late July or August until April or May of the following year. The gypsy moth has one generation per year.