Pine-tree lappet

Dendrolimus pini (Linnaeus)

Pine-tree lappet or pine moth is a European native, but is also known in the western part of Asia. It has not yet been detected in North America. The most likely method of introduction would be eggs and pupae hidden in the bark crevasses of unprocessed logs. Hosts are a wide range of conifers including fir, cedar, juniper, spruce, pine, Douglas-fir, and larch. From late-June through August, adult females lay eggs in groups of about 100. Females do not fly until after they have laid some of their eggs. The pinhead-sized (1/16 inch) eggs are blue-green when first deposited, later turning gray. Eggs hatch in about 14 days. Caterpillars first feed on egg shells, then on needles. First instar larvae can be wind dispersed as well as crawl significant distances to reach uninfested trees. One larva may consume up to 1,000 needles. When no needles are present, the bark of young shoots is also eaten. Mature larvae are 2-3 inches long with soft, gray to brownish hairs. Identifying features of the caterpillar include thick bands of steel blue and black hairs on the thorax and a black mark flanked by irregular white lines on the abdominal segments. After the first frost, caterpillars move to the litter on the forest floor to overwinter. The following spring, they return to the canopy to resume feeding. In June, yellow-brown to black cocoons marked with steel blue hairs start being formed in bark crevices and on needles and branches. Adults emerge in roughly 4 weeks. Identifying features of the 2 to 3 1/2 inch moth include gray-brown to brown forewings with a reddish brown lateral band and an irregular dark-brown to black stripe along the edges. Hind wings are red brown to gray brown. Males are usually darker than females.

Identification, Biology, Control and Management Resources

The Atlas of Forest Insect Pests - The Polish Forest Research Institute
Exotic Forest Pest Information System For North America - North American Forest Commission