Why are they a problem?
The browntail caterpillar has tiny (0.15 mm) hairs that on sensitive individuals cause a skin rash similar to poison ivy and/or trouble breathing.
The microscopic hairs break off the caterpillars and are everywhere in browntail infested areas; on trees, lawns, gardens, decks, picnic tables and in the air.
The hairs can remain toxic for up to THREE YEARS so although the problem is worst from May to July, they may cause a reaction at other times of year as well.
Wind or activities such as mowing, leaf-blowing, etc., can stir up the hairs, leading to a reaction.
The rash and trouble breathing can last anywhere from a few hours to several weeks. It is caused by both a chemical reaction to a toxin in the hairs and physical irritation from the barbed hairs. Contact your physician if a reaction is severe.
Maine Forest Service
Maine Board of Pesticides Control
Life Cycle: Browntail moth (Euproctis Chrysorrhea)
One generation a year.
Four life stages; egg, larval, pupal, and adult.
Larval stage (caterpillars) lasts from August through to the following June.
In the spring, as soon as the earliest leaf buds open, the caterpillars become active and leave their over-wintering webs to feed on tender new leaves. They may devour the leaves as fast as the leaves develop.
When young, the caterpillars return to the webs at night, but later remain out on the leaves overnight, and are fully grown by late June.
The caterpillars then form filmy cocoons between leaves on trees, under eaves, picnic tables, decks, etc.
Adult moths are emerge from cocoons in late July and August, laying clusters of eggs on the underside of leaves. The moths are strongly attracted to light.
Caterpillars emerge from the eggs in August and feed on the upper side of the leaves of host trees.
In the fall, colonies of caterpillars build winter webs on the tips of branches. The webs are made from leaves tightly wrapped with white silk. There can be 25 to 400 or more caterpillars in each web.
The caterpillars overwinter within the 2-5 inch (5-10 cm) winter webs. The webs are found most often on red oak or apple trees.
The caterpillars feed on the leaves of many hardwood trees and shrubs. Common host trees and shrubs in-clude:
Oak, apple, crabapple, cherry, hawthorn, shad-bush, serviceberry, and rugosa rose.
Feeding by browntail caterpillars can cause reduced growth and branch dieback. A number of years at high population levels can lead to mortality of trees and shrubs.
Eastern tent caterpillars have a solid whitish line down the middle of the back with a row of oval pale blue spots on each side and are covered with long brown hairs.
Gypsy moth caterpillars have pairs of blue and red spots along their back and are covered with long brown hairs.
Browntail Moth (adult):
Both sexes of the browntail moth have snow white wings and a tuft of dark brown hair on the tip of the abdo-men. Only seen in July and August.
Dark brown with a broken white stripe on each side and two conspicuous red spots on the back. They grow to 1.5 inches (3.8 cm) in length.
New Gloucester Environmental Committee 5/14/2017