Forest Pests: Insects, Diseases & Other Damage Agents

Gypsy Moth (Lymantria dispar)

Maier, C.T., C.R. Lemmon, J.M. Fengler, D.F. Schweitzer, and R.C. Reardon. 2004. Caterpillars on the Foliage of Conifers in the Northeastern United States. FHTET-2004-1. Morgantown, WV: USDA Forest Service, Forest Health Technology Enterprise Team; 151 p.

Description. Yellowish brown body with spines and hairs mounted on colorful tubercles and with darkly speckled dorsum. Yellowish brown head marked with dark brown except between lobes. Discontinuous, yellowish brown middorsal stripe speckled with black; black-spined, paired subdorsal tubercles that are blue from T1 to A2 and red from A3 to A8; reddish dorsal gland (in middorsal stripe) on A6 and A7. Brown and red supraspiracular tubercles with black spines and long, dull yellow hairs; brownish subspiracular tubercles with long, dull yellow hairs. Orange-brown venter with dark brown stripe down center. Up to 50 mm (male) or 55 mm (female).

Food. More than 500 trees and shrubs, but especially oaks; eastern hemlock, eastern larch, eastern white pine, and other species of Pinaceae, particularly during outbreaks.

Life Cycle. One generation. Egg overwinters on bark in large egg mass embedded with female abdominal hairs. Mature caterpillar present from June to August.

Comments. The gypsy moth is the most notorious defoliator of broad-leaved trees in the Northeast. In many northeastern areas, populations did not reach outbreak levels during the 1990s because the caterpillars suffered severe mortality from the introduced fungus, Entomophaga maimaiga.

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