Washington area governments say the gypsy moth infestation is likely to become more severe in the years ahead. Here are answers to basic questions about the gypsy moth and what you can do about the problem:
What are gypsy moths?
Gypsy moths are insects. Their rampage across the United States started more than a century ago. Federal officials date the infestation from 1869, when specimens imported from Europe escaped from a Massachusetts laboratory. Though isolated gypsy moth outbreaks have been reported throughout the United States, the most severe damage has occurred in the Northeast, where a record 13.1 million acres were defoliated in 1981. Because of cyclical biological patterns, the moths are not expected to match their 1981 record of destruction for seven to 10 years, officials said. This year, 8 million acres were reported defoliated in the Northeast.
How can gypsy moths be recognized?
As egg masses, they appear as a light brown, velvety mass, about 1 1/2 inches long and one-half to three-quarters of an inch wide, attached to a tree limb or trunk, firewood, stone wall, recreational vehicle, outdoor furniture or other outdoor object. The egg masses often are shaped like a pear, tear or raindrop.
When caterpillars emerge from eggs in the spring, they grow to about 1 1/2 to 2 1/2 inches long and are charcoal gray. At that time, they can be recognized by the double rows of dots that show on their backs -- five blue pairs and six red pairs. The adult female moth is white with black markings and has a wingspread of about two inches. The adult male is smaller with dark brown wings and a 1 1/2-inch wingspread.
What is the gypsy moth's life cycle?
Gypsy moths have an annual cycle. Their eggs are found in small masses from late August until early April. They emerge as larvae in late April and early May and grow into foliage-devouring caterpillars by late May and June. In late June or July, they form cocoons, from which they emerge as adult moths in 10 to 14 days. The adults do not feed. They mate and lay eggs. Male moths fly; females do not. The moths die soon after mating and egg laying.
What trees are most likely to be damaged by gypsy moths?
Their preference is for oak, apple, alder, aspen, basswood, hawthorn, willow and gray and river birch, according to the U.S. Agriculture Department. They may also attack other birches, beech, cherry, black gum, hemlock, hickory, hornbeam, larch, maple, pine, sassafras and spruce.
What steps may be taken to prevent gypsy moth damage?
Egg masses can be scraped off, collected and destroyed in ammonia, alcohol and similar liquids or burned in a fireplace. They should not be scraped onto the ground because they cannot be readily crushed and probably will hatch in spring. When caterpillars appear in May or June, one technique is to trap them by folding burlap to form a skirt around a tree; the caterpillars can be removed from the skirt and destroyed in a jar of alcohol. Pesticides are sometimes recommended, though officials urge caution.
In addition, Christmas trees, firewood, outdoor furnishings, recreational vehicles and other outdoor objects should be checked for signs of moth eggs or caterpillars, particularly if belongings have been transported from infested areas in the Northeast. Entomologists recommend burning or other proper disposal of discarded Christmas trees and firewood; they caution against dumping trees in wooded areas or chopping up trees for mulch without composting.