Tussock Moth Caterpillars

The rusty tussock moth caterpillar

 mikroman6/Getty Images

The Tussock Moth caterpillars, family Lymantriidae, are voracious eaters capable of defoliating entire forests. The most famous family member must be the Gypsy Moth, an introduced species to North America. This critter alone costs millions of dollars to control each year in the United States.

To insect lovers, the Tussock Moth caterpillars are known for their striking tufts of hair, or tussocks. Many species exhibit four characteristic clumps of bristles on their backs, giving them the appearance of a toothbrush. Some have longer pairs of tufts near the head and rear. Judged by looks alone, these fuzzy caterpillars seem harmless, but touch them with a bare finger and you'll feel you've been pricked by fiberglass. A few species, like the Brown-tail, will leave you with a persistent and painful rash.

Tussock Moth adults are often dull brown or white. Females are usually flightless, and neither males or females feed as adults. They focus on mating and laying eggs, dying within days.

White-marked Tussock Moth

Orgyia leucostigma White Marked Tussock Moth larva (Orgyia leucostigma)

 Forestry Archive, Pennsylvania Department of Conservation and Natural Resources, Bugwood.org

A native to North America, the White-marked Tussock Moth can still cause damage to trees when present in large numbers.

The White-marked Tussock Moth is a common native of North America, living throughout the eastern U.S. and Canada. The caterpillars feed on a range of host plants, including birch, cherry, apple, oak, and even some coniferous trees like fir and spruce.

White-marked Tussock Moths produce two generations each year. The first generation of caterpillars emerge from their eggs in spring, and feed on foliage for 4 to 6 weeks before pupating. In two weeks, the adult moth emerges from the cocoon, ready to mate and lay eggs. The cycle is repeated, with the eggs from the second generation overwintering.

Browntail Moth

Orgyia leucostigma White Marked Tussock Moth larva (Orgyia leucostigma)

Andrea Battisti, Università di Padova, Bugwood.org

The Browntail moth is an invasive pest of the New England states in the U.S.

Browntail moths, Euproctis chrysorrhoea, were introduced into North America from Europe in 1897. Despite their initial rapid spread through the Northeastern U.S. and Canada, today they are only found in small numbers in some New England states.

The Browntail caterpillar is not a picky eater, chewing on leaves from a variety of trees and shrubs. In large numbers, the caterpillars can quickly defoliate host plants in the landscape. From spring into summer, the caterpillars feed and molt, until they reach maturity in mid summer. They pupate on trees and emerge as adults in two weeks. The adult moths mate and lay eggs, which hatch by early fall. Browntail caterpillars overwinter in groups, sheltering in silken tents in the trees.

Browntail caterpillars have tiny hairs known to cause a severe rash, and should not be handled without protective gloves.

Rusty Tussock Moth

Orgyia antiqua Rusty Tussock Moth larva (Orgyia antiqua)
USDA Forest Service Archive, USDA Forest Service, Bugwood.org

An invader from Europe, the Rusty Tussock Moth feeds on both foliage and tender bark.

Rusty Tussock Moths, (Orgyia antiqua), are native to Europe but now live throughout North America, Europe, and parts of Africa and Asia. The Rusty Tussock Moth, also known as the Vapourer Moth, feeds on willow, apple, hawthorn, cedar, Douglas-fir, and a wide variety of other trees and shrubs. On coniferous trees, the caterpillars feed on new growth, including not only the needles but also the tender bark on twigs.

Like many other Tussock Moths, Orgyia antiqua overwinters in the egg stage. A single generation lives each year, with the larvae emerging from eggs in spring. Caterpillars may be observed throughout the summer months. Male adults fly during the daytime in the summer, but females cannot fly and lay their eggs in a batch over the cocoon from which they emerged.

Gypsy Moth

Lymantria dispar Gypsy Moth larva (Lymantria dispar)

University of Illinois/James Appleby

The Gypsy Moth's widespread population and voracious appetite make it a serious pest in the eastern United States.

The Gypsy Moth caterpillar feeds on oaks, aspen, and a variety of other hardwoods. A heavy infestation can leave summer oaks completely stripped of foliage. Several consecutive years of such feeding can kill trees entirely. The Gypsy Moth ranks as one of the "100 of the World's Most Invasive Alien Species," according to the World Conservation Union. It was first introduced into the U.S. around 1870​ and is now a major pest of the eastern states.

In spring, the larvae hatch from their winter egg masses and begin feeding on new leaves. Caterpillars feed primarily at night, but in a year of high Gypsy Moth populations, may continue feeding through the day as well. After 8 weeks of feeding and molting, the caterpillar pupates, usually on tree bark. Within one to two weeks, adults emerge and begin mating. The adult moths live only long enough to mate and lay eggs and do not feed. The larvae develop within the eggs in the fall, but remain with their eggs for the winter months and emerge when buds start to open in spring.

Nun Moth

Lymantria monacha Nun Moth larva (Lymantria monacha)

Louis-Michel Nageleisen, Département de la Santé des Forêts, Bugwood.org

Nun Moths do considerable damage to European forests, but fortunately have not been introduced into North America.

The Nun Moth, Lymantria monacha, is one Tussock Moth native to Europe that has not made its way to North America. That's a good thing, because in its native range it has reaped havoc on forests. Nun Moths tend to chew the base of needles on coniferous trees, allowing the rest of the untouched needle to fall to the ground. This habit results in extraordinary needle loss when caterpillar populations are high.

Unlike many other Tussock Moths, both males and females are active fliers in this species. Their mobility allows them to mate and lay eggs over wider ranges of forest, spreading the defoliation. Females deposit eggs in masses of up to 300; the insect then overwinters in the egg stage. The larvae emerge in spring, just when tender new growth appears on the host trees. This single generation devours foliage as it matures through as many as 7 instars.

Satin Moth

Leucoma salicis Satin Moth larva (Leucoma salicis)

Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org

The Satin Moth has an unusual life cycle. Satin Moth caterpillars feed twice each year, and hibernate in between feedings.

The Eurasian native Satin Moth, Leucoma salicis, was introduced to North America accidentally in the early 1920's. The original populations in New England and British Columbia gradually spread inland, but predation and parasites seem to be keeping this insect pest largely under control. Satin Moths feed on poplar, aspen, cottonwood, and willow.

The Satin Moth has a unique life cycle with one generation each year. Adult moths mate and lay eggs in the summer months, and caterpillars hatch from those eggs in the late summer and early fall. The tiny caterpillars feed for a short time before they hide in a bark crevice and spin a web for hibernation. The Satin Moth then overwinters in the caterpillar form, an unusual way to survive the cold. In spring, they re-emerge and feed again, this time reaching their full size of nearly 2 inches before pupating in June.

Definite-marked Tussock Moth

Orgyia definita Definite Marked Tussock Moth larva (Orgyia definita)

Forestry Archive, Pennsylvania Dept. of Conservation and Natural Resources, Bugwood.org

The Definite-marked Tussock Moth feeds on deciduous tree leaves in eastern U.S. forests.

The Definite-marked Tussock Moth, Orgyia definita, has a common name almost as long as the caterpillar. Some refer to the species as the Yellow-headed Tussock, which is a more descriptive name for the larva. In fact, it's more than the caterpillar's head that is yellow - its tufts of toothbrush-like hairs are a striking yellow as well.

Whatever the name they are given, these caterpillars feast on birches, oaks, maples, and basswoods throughout the eastern states in the U.S. Moths emerge from cocoons in late summer or early fall, when they mate and deposit their eggs in masses. The females will cover the egg masses with hairs from her body. Definite-marked Tussock Moths overwinter in the egg form. New caterpillars hatch in spring when food is available again. Through most of its range, the Definite-marked Tussock Moth has one generation per year, but in the southernmost areas of its reach, it may produce two generations.

Douglas-Fir Tussock Moths

Orgyia pseudotsugata Douglas Fir Tussock Moth larva (Orgyia pseudostugata)

Jerald E. Dewey, USDA Forest Service, Bugwood.org

The Douglas-Fir Tussock moth caterpillar feeds on firs, spruce, Douglas-firs, and other evergreens of the western United States.

Douglas-Fir Tussock moth caterpillars, Orgyia pseudotsugata, are major defoliators of spruce, true firs, and of course, Douglas-firs in the western U.S. The young caterpillars feed exclusively on new growth, but mature larvae will feed on older foliage. Large infestations of Douglas-Fir Tussock moths can cause severe damage to trees, or even kill them.

A single generation lives each year, with the larvae hatching in late spring when new growth has developed on the host trees. As the caterpillars mature, they develop their characteristic dark tufts of hair at each end. In mid to late summer, caterpillars pupate; the adults appear from late summer to fall. Females lay eggs in masses of several hundred in fall. The Douglas-Fir Tussock moth overwinters as eggs, entering a state of diapause until spring.

Pine Tussock Moth

Dasychira pinicola Pine Tussock Moth larva (Dasychira grisefacta)

USDA Forest Service Archive, USDA Forest Service, Bugwood.org

The Pine Tussock Moth caterpillar feeds twice during its lifetime - in late summer and again the following spring.

Predictably, the Pine Tussock Moth (Dasychira pinicola) feeds on pine foliage, along with other coniferous trees like spruce. It prefers the tender needles of jack pine, and during years of high caterpillar populations, entire stands of jack pines may be defoliated. The Pine Tussock Moth is native to North America, but still a species of concern to forest managers.

The caterpillars emerge in summer months. Like the Satin Moth, the Pine Tussock Moth caterpillar takes a break from feeding to spin a hibernation web, and stays within this silk sleeping bag until the following spring. The caterpillar finishes feeding and molting once warm weather returns, pupating in June.