History of the Gypsy Moth
In this article...
The gypsy moth is native to Europe, Asia and North Africa. It is a relative newcomer to North America, introduced to the United States in 1869 by a scientist in Medford, Massachusetts. From that beginning, the gypsy moth has spread to many areas of the United States and into eastern Canada.
In 1868, scientist Etienne Leopold Trouvelot brought the gypsy moth to Massachusetts to breed with other moths for a new strain of silk-producing caterpillars or "silkworms." The experiment failed and some of his caterpillars eventually escaped. They found the environment in this new country to their liking, with much food and few natural enemies.
The gypsy moth is one of the most disliked insects in the United States. Millions of dollars have been spent by federal, state and local governments trying to exterminate them, yet the spread continues.
Ten years ago it was thought that the gypsy moth spread was advancing west and south from the Northeast region at a rate of 5 to 15 miles per year. But egg masses on travel trailers and campers have helped speed up the process, creating pockets of infestations. This is what happened in Michigan. Because of large areas of susceptible forests and few natural enemies, the gypsy moth has become well established in many new areas.
While oak tree leaves are the favorite food of a gypsy moth, they will feed on more than 600 species of trees, shrubs and vines. Only a few species of trees are immune to feeding.
The traveling abilities of the gypsy moth begin even as an egg mass, when deposited by the female moths on trees, houses, outdoor equipment, cars and tr ucks, travel trailers and campers and just about anywhere the non-flying female happens to be. Often the egg masses have traveled hundreds of miles before the larvae hatch and crawl off to start a new infestation in the spring.
The tiny gypsy moth larva can travel short distances soon after hatching. The caterpillars seek light (are positively phototrophic) and instinctively move away from the ground (are negatively geotrophic) soon after hatching. The caterpillars climb trees or other objects until they reach the tips of branches. This tree climbing behavior aids in a process called "ballooning." The young larva suspend themselves from the tree branch on a silk thread. With very little body weight and long hairs to catch the wind, they float through the air (sometimes for miles) to a new location.
When the caterpillar grows, pupates and emerges as an adult moth to lay an egg mass, a new life cycle begins.
In Michigan ...
When you hear the word "gypsy", a busy traveler may come to mind, and the gypsy moth fits that picture. The ability to travel is a key characteristic of the gypsy moth and explains how the infestation was able to spread from Massachusetts to Michigan.
The gypsy moth is found in every county in the Lower Peninsula and in areas of the Upper Peninsula. While there is encouraging news that some areas are showing a decline in numbers and damage, other areas of Michigan have yet to experience infestations in the 1990s.
The spread of the gypsy moth occurs when egg masses are laid on vehicles or outdoor items which are later moved, in the caterpillar stages by the wind and as adult moths. The exact source of Michigan's first gypsy moths likely never will be known, but they could have come from egg masses brought by campers returning from the northeast United States. In addition, the spread in Michigan can in part be attributed to the young gypsy moth caterpillar's ability to suspend on a strand of silk and be carried by the wind, sometimes for several miles.
Though the female moth can't fly, the male is a strong daytime flyer and can fly long distances. The males also have a keen ability to detect and follow the scent of a female with their antennae.
Michigan's greatest lure to the gypsy moth is its vast forest resources; hundreds of thousands of acres of the larva's favorite diet. The list of favorite foods is led by oak and poplar trees. Michigan abounds with these and other susceptible trees, including birch, willow, crabapple and maple.
Gypsy moths have been on the East Coast of the United States for more than 100 years and have been in Michigan for nearly 50 years. In the early 1950s, the Michigan Department of Agriculture (MDA) became involved in what has been a continuing effort to control the insect. During the 1950s and the 1960s, 7it appeared that the gypsy moth had been eliminated after monitoring and targeted spray programs.
Then, in the 1970s, gypsy moth traps baited with new attractant chemicals proved that the insect was thriving in Michigan. To combat the insect, the MDA has developed a suppression program to slow the gypsy moth spread and lessen defoliation damage for homeowners in Michigan.
In the 1980s, the defoliated acres contined to grow and the gypsy moth began to be noticed as a pest that deserved extra attention. Besides the inconvenience and lack of shade from having trees defoliated in early summer, there were negative effects on tourism, forest products, Christmas tree sales, and other plants and wildlife.
In 1992 the gypsy moth was responsible for the largest total area of defoliation in Michigan history. The 1990s also began with marked increases in tree mortality attributed in part to the gypsy moth. Increases in acreage of forested public recreation lands sprayed to limit nuisance problems and a rise in demand for forest management and gypsy moth suppression information also occured.
Besides surveying, monitoring, trapping and spraying, there have been natural enemies introduced and emphasis put on education to help people identify problem areas and make good decisions on ways to deal with the gypsy moth.
Document Author(s): Program Staff
Revised: September 10, 1997
URL: http://www.ent.msu.edu/gypsyed/docs/history.html