Gypsy Moth

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Gypsy Moth History

seasons of the gypsy moth

​Gypsy moths don't belong in North America. They are native to parts of Europe, Asia, and northern Africa and were first brought to the United States in the 1860s. Trouvelot, a French scientist, wanted to breed gypsy moths with silk moths with the hopes of creating a lucrative silk market in the United States. He chose gypsy moths because, unlike silk moths which are very particular about what they eat, gypsy moths feed on leaves of over 500 types of trees and shrubs. Trouvelot believed that a cross between the two moth species would create a hardy silk-producer that would be easy to raise and inexpensive to feed. 

Unfortunately for Trouvelot, silk moths and gypsy moths are not even in the same insect family and cannot breed with each other. Although his dreams of creating a lucrative silk market in the United States were never fulfilled, Trouvelot did unintentionally start another multi-million dollar industry - that of gypsy moth control.

What is a Gypsy Moth?

seasons of the gypsy moth Lymantria dispar, the gypsy moth, is responsible for millions of acres of defoliation annually. Although gypsy moths are capable of feeding on over 500 different species of trees and plants, they prefer oak trees. Although it usually takes more than one year of defoliation before trees die, conifers that are defoliated may be killed after a single season of defoliation. Gypsy moths have one generation per year, and this includes egg, caterpillar, pupae and adult stages. Female moths lay egg masses on tree boles, branches, vehicles, houses, and other structures, and this aids their spread to new areas. Egg masses are buff-colored after they are initially deposited in late summer, but they become lighter in color as they bleach in the sun. Egg mass size may indicate population trends.

When populations are declining, most egg masses are around 1/2 inch long and contain about 100 eggs, while building populations have 1 1/2 inch long egg masses containing up to a thousand eggs. Gypsy moths survive the winter in the egg stage and hatch from mid-April to mid-May in Illinois when temperatures are above 60 degrees Fahrenheit. Mature caterpillars pupate from mid June through early July in Illinois. Mice, shrews, and ground beetles eat the pupae, and are an important regulator of gypsy moth in this stage. Adult gypsy moths emerge about two weeks after pupating.

Adults only live about a week, and do not feed. Female gypsy moths use chemicals to attract a mate soon after they emerge. They lay eggs about a day after mating. Adult gypsy moth males have feathery antennae and brown wings and are able to fly, while cream-colored females of European gypsy moths cannot fly and have threadlike antennae. If it's a white moth and flying, it is not a Gypsy Moth.

Voracious Feeders

tree damage by a gypsy mothGypsy moth caterpillars consume as much leaf tissue as they can, as quickly as they can, to obtain nourishment to become reproducing adults. Since the caterpillars' feeding period lasts seven to ten weeks through spring and summer, they can do a lot of damage to young tree leaves. If a tree loses more than 50% of its leaves for more than two years in a row, it will certainly be weakened and may not survive.

A single gypsy moth caterpillar can consume 11 square feet of vegetation during its lifetime so the presence of millions of caterpillars can severely affect trees and forests

​Although gypsy moths can exist at relatively low population levels for years at a time, sometimes their populations explode. This occurs for various reasons (favorable weather conditions or a lack of predators, for example). This rapid swelling of population size is called an "outbreak".

During large outbreaks, trees are virtually stripped of their leaves by hungry caterpillars within a few days. Although most trees will re-grow new leaves before summer's end, the process stresses the tree and drains its reserves. Weakened trees and shrubs, especially those in urban settings, are more susceptible to attack by opportunistic diseases and organisms. In addition, the tree's growth rate is impaired, which affects its chances for survival during the following years.

The Illinois Department​ of Agriculture and The Gypsy Moth

The Illinois Department of Agriculture is very active in monitoring and controlling this invasive pest. In 1992, the U.S. Department of Agriculture's (USDA) Forest Service (FS) and Animal and Plant Health Inspection Service (APHIS), along with the Department of Interior's National Park Service and eight State and university partners, embarked on a pilot project called "Slow the Spread." The project's goal was to slow the rate of natural gypsy moth spread by using integrated pest management strategies. The project demonstrated that it is feasible to significantly reduce the spread of gypsy moth and that this can be accomplished in a cost-effective and environmentally viable manner using current technology.

In 1999, following successful completion of the pilot project, the National Gypsy Moth Slow the Spread program was implemented along the entire 1,200 mile gypsy moth frontier from North Carolina through the upper peninsula of Michigan

gypsy moth trapsToday, the Illinois Department of Agriculture, along with the STS Foundation, places over 7,000 traps to monitor populations each year. Each year, the monitoring is tabulated and eradication treatments are decided for the following year.

The gypsy moth is migrating west, and it has established itself in Illinois. Lake County, Illinois was quarantined in 2000. The counties of McHenry, Cook and Du Page were added in 2007. A quarantine requires all nursery stock and firewood being shipped out of the affected counties to be inspected and certified, which is a difficult and time-consuming procedure. All nurseries and nursery dealers are also required to treat their property and/or stock, and persons leaving quarantined counties must have all outdoor equipment inspected.

If you see a Gypsy Moth in any stage of life, call toll free: 1-866-296-MOTH (6684). 

More information can also be obtained by contacting:

Illinois Department of Agriculture
Northern IL Field Office
2280 Bethany Road, Suite B
DeKalb, IL 60115

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