NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
April 20, 2000
Gypsy moths have devastated trees in many parts of the eastern United States, and now this non-native insect could threaten trees in the Midwest and the northern Great Plains, including North Dakota and Minnesota, says a forester at North Dakota State University. Because of this threat, state and federal agencies have been conducting annual trapping surveys to monitor the problem.
"No established populations of this insect are currently known to exist in North Dakota, but tests have shown that gypsy moths could overwinter in the state,"says Marcus Jackson, extension forester at NDSU.
Jackson encourages homeowners and land managers to cooperate in this year's survey by allowing surveyors to place traps in their yards or other areas containing trees and shrubs. The so-called delta trap used in North Dakota resembles a pup tent and is made of a heavy, coated paper similar to milk cartons. Designed to capture male gypsy moths, the traps hang from tree branches and contain a lure that mimics an attractant naturally produced by the female gypsy moth. This lure has no effect on humans or other animals, plants or even other insects.
"Gypsy moth has been found in North Dakota on nursery stock shipped in from infested states and in areas frequented by out-of-state visitors, such as campgrounds," Jackson says. Specifically, a male gypsy moth was trapped in North Dakota for the first time in seven years in 1997 near Jamestown. Since then, gypsy moths have been caught in subsequent trapping surveys. One gypsy moth was trapped in Theodore Roosevelt National Park in 1998, and two were trapped in 1999, one near Devils Lake and the other near Bismarck.
Female gypsy moths, which are established in the eastern United States, do not fly. Instead, the insect's mobility results from caterpillars being blown by the wind and eggs being unknowingly carried by humans, Jackson explains. The female gypsy moth will deposit its eggs on many types of surfaces, including automobiles, lawn furniture and firewood, as well as nursery stock.
Introduced into the United States in 1869 by a naturalist who was attempting to breed silk worms, the gypsy moth subsequently escaped into the forests of Massachusetts and has been moving west ever since, Jackson says. Currently, 15 states are infested with the insect. Gypsy moth caterpillars are capable of defoliating more than 300 species of trees and shrubs. Repeated defoliation can weaken and ultimately kill trees.
Research shows that there are many potential hosts for gypsy moths in North Dakota, Jackson says. Favored hosts include the following trees: apple, aspen, basswood, birch, boxelder, hawthorn, oak, poplar, sumac and willow. Other trees that could be potentially harmed include buckeye, chokecherry, elm, hackberry, larch, maple, pine and spruce. Gypsy moths generally avoid arborvitae, ash, black walnut, catalpa, dogwood, honey-locust, juniper and Russian-olive trees.
Jackson expects that the results of this year's trapping program will be compiled by October. For more information about North Dakota's gypsy moth trapping survey, contact him at (701) 231-8478.
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Source: Marcus Jackson (701) 231-8478
Editor: Dean Hulse (701) 231-6136