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A: There is one generation each year. The gypsy moth spends the winter in the egg stage, caterpillars hatch from eggs in the spring, feed, change into pupae, and then changes into moths. Female moths lay eggs in the summer and the cycle begins again.
A: In Virginia, eggs hatch in late April or early May. The hatch continues for two to three weeks. Young caterpillars that hatch from these eggs climb up the trunks of trees and are blown by the wind to other trees where they begin to feed on the leaves.
A: The female gypsy moth will lay between 150-1,500 eggs in a single egg mass. The egg mass is covered with her body hair and is buff in color.
A: There are some other moths that produce egg masses, and, like the gypsy moth, these spend the winter as eggs. However, the gypsy moth egg masses are rarely confused with these other species because of their buff color and relatively large size.
A: Gypsy moth caterpillars are about 1/4" long when they hatch from their egg.
A: Gypsy moth caterpillars can reach 2 1/2 inches long at maturity.
A: There is just one generation per year, feeding occurs during May and June. The caterpillar stage is usually completed by the end of June.
A: Yes, at least three. However, the behavior of these caterpillars, and when and where they are found, are important characteristics to know. The eastern tent caterpillar appears early in the spring, usually far in advance of the gypsy moth. It lives in a large, silken tents in the crotches of many trees. Fall webworm caterpillars appear late in the summer, much later than the gypsy moth, and also live in a protective webbing. Finally, caterpillars of the mourning cloak butterfly live in large groups, and for this reason, they might be confused with the gypsy moth. However, the gypsy moth caterpillar is very hairy, has red and blue spots, and is larger and therefore easily distinguished from caterpillars of the mourning cloak.
A: Gypsy moth caterpillars will feed on over 300 trees and shrubs. However, they will do best when feeding on oaks. During heavy infestations the large caterpillars (nearly full grown) may feed on pine, spruce, and hemlock trees that are growing in or near deciduous woodlands.
A: Yes, a few. Plants which are not usually eaten by gypsy moth caterpillars include arborvitae, ash, locust, catalpa, cedar, dogwood, holly, sycamore, tulip polar, and walnut.
A: That depends on the kind of tree. Healthy, deciduous trees can usually withstand one or two complete defoliations (that is, they loose all their leaves). By mid-summer, these trees will put out new leaves; however, the foliage is usually less dense and the leaves smaller, and lighter in color. If defoliation occurs in more than two consecutive years, the tree may die, but if not, it becomes weak and more susceptible to other insect pests, diseases and drought. Evergreen trees are much less tolerant of defoliation. Most evergreens are unable to survive a single season of intensive gypsy moth feeding.
A: Adult gypsy moths do not feed. Mating and egg-laying occur during July and into August soon after the adults emerge; the moths then die.
A: Dispersal and spread of the gypsy moth may be either natural or artificial. Natural spread occurs when the very small (early stage) caterpillars are windblown from the tops of trees as they hang on silken threads from leaves. Artificial spread over long and short distances occurs when people transport egg masses or caterpillars on plants, automobiles, firewood, household goods, and other belongings. One infestation began in Virginia when an unsuspecting homeowner moved several dog houses from New Jersey that contained gypsy moth egg masses.
A: Homeowners can use some manual methods to reduce numbers of gypsy moths around their home. Egg masses can be scraped off surfaces with a putty knife and dropped into a container of bleach. Caterpillars can be trapped under burlap bands or other dark cloth wrapped around the trunks. When infestations are severe, these methods are not adequate to prevent damage and are only useful on individual trees.
A: No. Judicious use of insecticides can help to slow the establishment and spread of infestations. This will delay the inevitable cost of controlling outbreaks and more intense use of chemicals.
A: Yes. There is a complex of natural enemies, which is composed of parasites, predators, and disease organisms. They often control the gypsy moth after 2-3 years of severe outbreaks, and they help in keeping some populations at low levels. Disease is a major factor in halting outbreaks, but this occurs only after the full impact of a large population has been realized. In North America there are a number of insect parasites that attack various stages of the gypsy moth. At present, they have not prevented outbreaks nor controlled infestations before severe defoliation has occurred.
A: A number of birds feed on the gypsy moth during various life stages. However, birds usually leave areas that are completely defoliated.
A: Under normal conditions, when few caterpillars or egg masses are observed, annual protective spraying of pesticides on trees and shrubs is not justified and may reduce the natural enemy complex of the gypsy moth.
A: If you have susceptible trees; egg masses or caterpillars have been found; and nearby areas have shown defoliation you may have a problem. You should contact your county Extension office for more information.
| Andy Roberts | |
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540-231-4615 Last Modified: 16 April 2001 |
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