Spongy Moth

The spongy moth, previously referred to as the gypsy moth, is a non-native insect from France that was introduced in the United States in 1869 to breed with silkworms to develop a silk industry. After breeding failure, some spongy moths escaped and established a population in Medford, Massachusetts. The current extent of Gypsy Moth stretches from North Carolina and across to Minnesota and encompasses 19 states including New York. In New York, spongy moth caterpillars feed on the leaves of oak, maple, apple, crabapple, hickory, basswood, aspen, willow, birch, pine, spruce and other tree species.

The larval stage of the spongy moth is a caterpillar, found in the spring that grows to about 2.5 inches in length with five pairs of raised blue spots followed by six pairs of raised red spots along its back. Female adult spongy moths are white with brown markings while male moths are brownish. The egg masses of spongy moths are light brown in color and appear as fuzzy patches on tree trunks, branches and even on lawn furniture.

Spongy moths are considered to be a naturalized part of our forest communities, meaning they will always be around. However, their populations tend to rise and fall in 10-15-year cycles. These “outbreaks” of the population are usually slowed by natural causes such as disease of predation.

During outbreaks where populations are high, thousands of acres of tree species can be affected. Deciduous trees—trees that lose their leaves every fall— can regrow a new set of leaves during the summer to replace the leaves destroyed by the spring caterpillars and can usually withstand 2 to 3 years of defoliation without tree death. Yet, tree stress through defoliation can leave the tree susceptible to other pests and diseases. Death of tree populations become a risk when gypsy moth outbreaks occur simultaneously with other prominent disease and pest problems.

The New York State Department of Environmental Conservation and state partners do not typically manage spongy moth populations other then in cases of ecological or culturally significant forested areas. The caterpillars of spongy moths are generally controlled through natural predation by birds, rodents, parasites and diseases.

While populations of spongy moths are low, gypsy math caterpillars and adults can be killed through squishing them or by scraping egg masses off trees or other structures and dropped into detergent. There are various insecticides available for spongy moths at garden centers as well as horticultural oil insecticides and chemical insecticides. Further information on insecticide treatment and treatment timing can be found in the US Forest Service’s guide to gypsy moths.

Resources

DEC – Gypsy Moth, This webpage from the New York State Department of Environmental Conservation highlights the introduction of this species to the U.S., its identification, current control methods and how to get involved in helping trees recover from infestations.

USDA APHIS- Gypsy Moth, This webpage from the United States Department of Agriculture Animal and Plant Health Inspection Service (APHIS) providers readers with information about the Asian and European Gypsy Moth including pest identification, regulations, maps, management practices and publication and outreach links and materials.

European Gypsy Moth – Invasive Species Profile, This webpage on the National Invasive Species Information Center hosted through the U.S. Department of Agriculture, provides information about the means of introduction, research spotlights and educational information via videos, imagery and other documentation.

USDA Forest Service – Gypsy Moth, The webpage from the Northern Research Station of the USDA Forest Service provides information about this invasive species and its contribution to forest disturbance processes. This webpage provides readers the opportunity to explore current research on four areas of study including: risk, detection and spread; biology, ecology and dynamics; control and management; and effects and impacts.

NPS- Gypsy Moth, This webpage from the National Park Service provides information about this invasive species and how it locally impacts the Isla Royale National Park in Michigan

Last updated April 13, 2022