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The gypsy moth (''Lymantria dispar'') was introduced in 1868 into the United States by Étienne Léopold Trouvelot, a French scientist living in Medford, Massachusetts. Because native silk-spinning caterpillars were susceptible to disease, Trouvelot imported the species in order to breed a more resistant hybrid species. Some of the moths escaped, found suitable habitat, and began breeding. The gypsy moth is now a major pest of hardwood trees in the eastern United States.〔(【引用サイトリンク】 url=http://datcp.wi.gov/Environment/Gypsy_Moth/index.aspx )〕 The first US outbreak occurred in 1889, and by 1987, the gypsy moth had established itself throughout the northeast US, southern Quebec, and Ontario. The insect has now spread into Michigan, Minnesota, Virginia, West Virginia, and Wisconsin. Small, isolated infestations have sporadically occurred in Utah, Oregon, Washington, California, and British Columbia, but these have been eradicated. Since 1980, the gypsy moth has defoliated over one million acres (4,000 km2) of forest each year. In 1981, 12.9 million acres (52,200 km2) were defoliated. In wooded suburban areas, during periods of infestation, gypsy moth larvae crawl over man-made obstacles and sometimes enter homes. When feeding, they leave behind a mixture of small pieces of leaves and frass, or excrement. During outbreaks, the sound of moths chewing and dropping frass may be loud enough to sound like light to moderate rainfall.〔(【引用サイトリンク】title=How and Why Gypsy Moth Treatment Sites are Selected )〕 Gypsy moth populations usually remain low, but occasional increases to very high levels can result in partial or total defoliation of host trees. According to a 2011 report, the gypsy moth is now one of the most destructive insects in the eastern United States; it and other foliage-eating pests cause an estimated $868 million in annual damages in the U.S. == Host species == Gypsy moth larvae prefer oak trees, but may feed on many species of trees and shrubs, both hardwood and conifer. In the eastern US, the gypsy moth prefers oaks, aspen, apple, sweetgum, speckled alder, basswood, gray, paper birch, poplar, willow, and hawthorns, amongst other species. The gypsy moth avoids ash trees, tulip-tree, cucumber tree, American sycamore, butternut, black walnut, catalpa, flowering dogwood, balsam fir, cedar, American holly, and mountain laurel and rhododendron shrubs, but will feed on these in late instars when densities are extremely high. Older larvae feed on several species of softwood that younger larvae avoid, including cottonwood, hemlock, Atlantic white cypress, and pine and spruce species native to the east.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gypsy moths in the United States」の詳細全文を読む スポンサード リンク
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