Gypsy Moth FAQ

Table of Contents

1. How do I know if I have gypsy moth in my yard?
2. Will gypsy moth cause my trees to die?
3. How can I keep my trees healthy?
4. What can I do to reduce gypsy moth populations in my yard?
5. Can't I just get rid of all the gypsy moths?
6. Where can I get more information?

How do I know if I have gypsy moth in my yard?

Many insects are found on urban trees, but there is only one gypsy moth! Gypsy moth caterpillars have pairs of red and blue spots along their back, long dark hairs and are present from May until early July. The caterpillars spin reddish-brown cocoons in July and pupate for one to two weeks. Adult moths live only a few days and do not feed. Adult males are brown with dark markings on the wings and are active fliers. Adult females have white wings with black chevron markings, but do not fly. Adults may be present in July and early August. Each female lays one tan egg mass, which is covered with tiny hairs. Egg masses may be small, about the size of a quarter, or may be up to three inches long. Egg masses are laid in July or August and will hatch the following April or May. Color photos of the life stages of gypsy moth can be found in MSU Extension Bulletin E-2302 and E-1983.

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Will gypsy moth cause my trees to die?

NO! If an oak or other hardwood tree is completely defoliated during the summer, it may look like it's dead. But, healthy trees will produce a second set of buds, usually in late July or August. This second set of leaves will produce enough energy for the tree to survive the winter. Severe defoliation does stress the tree, but healthy trees can tolerate even complete defoliation for a few years. However, if trees are affected by other stress factors such as drought, disease or poor growing conditions, there is a greater chance that they will die.

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How can I keep my trees healthy?

The best thing that you can do for your trees to keep them well-watered, particularly during dry periods m the summer. Also, avoid wounding your trees with lawn mowers or other equipment. Wounds will increase the risk that trees will be affected by disease. Avoid compacting the soil or damaging the root system of trees.

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What can do to help reduce gypsy moth populations in my yard?

You bet! Search for egg masses on trees, on firewood and on outdoor furniture. Scrape egg masses into a coffee can filled with soapy water or burn or bury the egg masses. Bands can be used to trap caterpillars or prevent them from climbing into the canopy. See MSU-Extension Bulletins E-2300, E-2301, E-2302 and E-2591 for information on these strategies.

Pheromone traps are used by scientists and pest managers to detect new gypsy moth populations in uninfested areas. These traps are rarely effective in controlling gypsy moth populations, however. See MSU-Extension Bulletin No. E-2585 for more information.

Many natural enemies such as birds, mice, predatory insects and insect parasitoids feed on gypsy moth. You can encourage these natural enemies by avoiding the use of broad-spectrum insecticides and by providing habitat for birds and predators. Several biological control agents have been introduced into Michigan to help control gypsy moth. Entomophaga maimaiga the gypsy moth fungus, is a recent introduction that has been effective at controlling caterpillars in some years. See MSU-Extension Bulletins E-2302 and E-2604 for information on gypsy moth natural enemies.

Some residents use Bt (Bacillus thuringiensis var. kurstaki) to reduce gypsy moth populations. Bt is a bacterial disease that only affects foliage-feeding caterpillars. It must be sprayed on leaves and the leaves must be eaten by young caterpillars to be effective. Bt is not harmful to humans or other mammals, birds, fish, or beneficial insects. More information on Bt is available in MSU Extension Bulletins E-2421 and E-2591.

You can spray Bt on your trees yourself or hire professional tree care companies to spray trees. Also, some municipalities or neighborhoods areparticipating in the Michigan Voluntary Gypsy Moth Suppression Program administered by the Department of Agriculture. This program helps pay costs of Bt application in residential areas during gypsy moth outbreaks. Your neighborhood may be eligible to participate if you meet the program requirements. Contact your county Suppression program coordinator, the regional Department of Agriculture office, or your county MSU-Extension office to learn more about this program.

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Can't we just get rid of ALL the gypsy moths?

Nope - gypsy moth is here to stay and is now a part of Michigan's forest and urban forest ecosystems. But, you can help keep gypsy moth from spreading into new areas that are not yet infested. Gypsy moth females like to lay their egg masses in dark protected locations. Sometimes, the egg masses are on the underside of lawn chairs, picnic tables or on firewood. Egg masses may also be found on recreation vehicles, trailers or in wheelwells of cars.

If you transport the egg masses to a new location, you may be accidentally carrying gypsy moth along with you. This could be the beginning of a new gypsy moth population and the start of many headaches for other people! Be sure that you know what a gypsy moth egg mass looks like. Inspect firewood, vehicles, lawn furniture and other outdoor items that might have egg masses. If you find egg masses, scrape them off into a can of soapy water, or burn or bury them.

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Where can I get more information?

Contact your county MSU-Extension office. They can provide you with the Extension bulletins listed here and give you up-to-date information on the gypsy moth situation in your neighborhood.

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Document Author(s): Program Staff
Revised: September 10, 1997
URL:  http://www.ent.msu.edu/gypsyed/docs/faq.html