Lymantriidae caterpillars, which defoliate entire forests, feed on Tussock Moth caterpillars. A member of this family is the Gypsy Moth, a beautiful but highly destructive insect not native to North America. It became clear after its introduction that these creatures could cause a great deal of destruction. Every year, the Gypsy Moth alone costs millions of dollars to control in the United States.
A Tussock Moth caterpillar, on the other hand, is most famous for its striking tufts of hair, or tussocks. Some species have four characteristic clumps of bristles on their backs, giving them the appearance of toothbrushes.
The tufts near the head and rear of some birds are longer. The fuzzy caterpillars might appear harmless, but touch one with a bare finger and you’ll feel as if you’ve been pricked by fiberglass. There are even some species that can leave you with a painful and persistent rash, such as the Brown-tail.
It is common for Tussock Moth adults to be dull brown or white in color. Neither males nor females feed as adults, and females are usually flightless. After mating and laying eggs, they die within days.
White-Marked Tussock Moth
Throughout the eastern United States and Canada, the White-Marked Tussock Moth is a common native of North America. It feeds on a variety of host plants, including birch, cherry, apple, oak, and even coniferous trees like fir and spruce, and may cause damage to trees if present in large numbers.
Every year, two generations of White-Marked Tussock Moths are produced. As soon as the eggs hatch, the first generation of caterpillars emerges. During the four to six weeks before pupation, they feed on foliage. Two weeks after emerging from the cocoon, the adult moth is ready to mate and lay eggs. After the second generation overwinters, the cycle is repeated.
The browntail moth (Euproctis chrysorrhoea) was introduced into North America from Europe in 1897. Today, they are only found in small numbers in some New England states, where they remain persistent pests despite their rapid spread initially throughout the Northeast and Canada.
The Browntail caterpillar eats leaves from a variety of trees and shrubs. When large numbers of caterpillars are present, host plants in the landscape can be quickly defoliated. A caterpillar feeds and molts from spring to summer.
After reaching maturity in mid-summer, they pupate on trees and emerge as adults two weeks later. In the early fall, the adult moths mate and lay eggs that hatch. It is common for browntail caterpillars to overwinter in groups, sheltering in silken tents in trees during the winter.
Browntail caterpillars have tiny hairs that can cause severe rashes in humans, making them unsuitable for handling without protective gloves.
Rusty Tussock Moth
Originally native to Europe, the Rusty Tussock Moth (Orgyia antiqua), also known as the Vapourer Moth, has now spread to North America, Europe, as well as parts of Africa and Asia. As well as willow, apple, hawthorn, cedar, Douglas-fir, and an assortment of other trees and shrubs, this European invader feeds on both foliage and bark. Among coniferous trees, the caterpillars feed on new growth, devouring needles as well as tender bark.
In the egg stage, Orgyia antiqua overwinters like many other Tussock Moths. In spring, larvae emerge from eggs, forming a single generation each year. It is possible to observe caterpillars throughout the summer. Females lay their eggs in batches over the cocoon from which they emerged during the day, while males fly during the day.
Around 1870, the Gypsy Moth was introduced to the United States for the first time. In the eastern United States, it has become a major pest due to its widespread population and voracious appetite. The caterpillars of the Gypsy Moth feed on oaks, aspens, and a variety of other hardwoods.
It is possible for summer oaks to lose all their foliage due to a heavy infestation. It is possible to kill trees entirely if they are fed in this manner for many consecutive years. Among the World Conservation Union’s “100 Most Invasive Alien Species,” the Gypsy Moth ranks first.
Larvae hatch from winter egg masses in spring and begin feeding on new leaves. Gypsy Moth caterpillars typically feed at night, but they may also feed during the day in years with high populations. Eight weeks after feeding and molting, the caterpillar pupates, usually on tree bark. A couple of weeks after emerging, adults begin mating.
It is not necessary for the adult moths to feed. The laying of eggs and mating of the females are the only things they do in their lives. Larvae develop in fall and remain inside the eggs over winter, emerging when buds open in spring.
Tussock moths are native to Europe but have not made their way to North America. The Nun Moth (Lymantria monacha) is one of them. This is good news, since its native range wreaked havoc on forests. It is common for Nun Moths to chew the base of needles on coniferous trees, leaving the rest untouched. When caterpillar populations are high, this eating habit results in extensive needle loss.
Both males and females of Tussock Moths are active fliers, unlike many other species. Due to their mobility, they are able to mate and lay eggs over a wider area of their forest habitat-which unfortunately has the effect of spreading defoliation. In the egg stage, females deposit up to 300 eggs, which overwinter as eggs.
In spring, just as the host trees begin to sprout new growth, the larvae emerge. It devours foliage as it passes through seven instars (phases between two phases of molting in the maturation process of an insect larva or other invertebrate).
In the early 1920s, the Eurasian Satin Moth (Leucoma salicis) was accidentally introduced to North America. While predation and parasites seem to be keeping this insect pest largely in check, its original populations in New England and British Columbia gradually spread inland.
The Satin Moth has a unique life cycle with one generation per year. Summer is the time when adult moths mate and lay eggs, and caterpillars hatch from those eggs in the late summer and early fall. Caterpillars feed for a short time, usually on poplar, aspen, cottonwood, and willow trees, before retreating inside bark crevices and spinning a web for hibernation. Unlike other moths, satin moths overwinter as caterpillars. In spring, they re-emerge and feed again, reaching their full size of nearly two inches before pupating in June.
Definite-Marked Tussock Moth
The Definite-Marked Tussock Moth (Orgyia definita) has a long common name. This caterpillar is sometimes called a Yellow-Headed Tussock, but it also has toothbrush-like tufts of yellow hair along with its yellow head. In the eastern United States, these caterpillars feast on birch, oak, maple, and basswood trees.
Moths emerge from their cocoons in late summer or early fall, when they mate and lay their eggs in large numbers. Females cover their egg masses with hair from their bodies. Tussock Moths with definite markings overwinter as eggs. When food becomes available again in spring, new caterpillars hatch. In most of its range, the Definite-Marked Tussock Moth produces one generation a year, but in the southernmost areas of its range, it may produce two generations a year.
Douglas-Fir Tussock Moths
Douglas-Fir Tussock Moth caterpillars (Orgyia pseudotsugata) defoliate firs, spruces, Douglas-firs, and other evergreens of the western United States. Caterpillar larvae feed exclusively on new growth, but older foliage is also consumed by mature caterpillars. It is possible for Douglas-Fir Tussock Moth infestations to cause severe damage to trees-and even cause their death.
Every year, only one generation lives. Late spring is the best time to hatch the larvae since new growth has developed on the host tree. The caterpillars develop dark tufts of hair at each end as they mature. Caterpillars pupate in mid- to late summer, and adults appear in late summer and fall. Autumn is the time when females lay eggs in masses of several hundred. Overwintering as eggs, Douglas-Fir Tussock moths enter a state of diapause (suspended development) until spring.
Pine Tussock Moth
Despite being a native of North America, the Pine Tussock Moth (Dasychira pinicola) still poses a threat to forest managers. Caterpillars of the Pine Tussock Moth feed twice during their life cycle: late in summer and again in spring.
In addition to pine foliage, Pine Tussock Moth caterpillars also eat spruce and other conifers. When caterpillar populations are high, entire stands of jack pine may be defoliated when they prefer the tender needles.
Summer is the time when caterpillars emerge. Satin Moth caterpillars spin hibernation webs and stay inside silk sleeping bags during hibernation, similar to Pine Tussock Moths. Once warm weather returns, the caterpillar finishes feeding and molts, pupating in June.