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Controlling the Gypsy Moth
| Article
# : |
16035 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
7 / 1989 |
3,002 Words |
| Author
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Helen Webb
Helen Webb is a free-lance science writer residing in
Greenbelt, Maryland. |
"Measles in the forest" is how David A. Gansner of the U.S. Forest Service describes the patterns of defoliation caused by the gypsy moth. This insect native to Europe, Asia, and Africa has been eating its way slowly through the northeastern United States for the past 120 years. The damage the gypsy moth can cause during peak outbreaks is legendary in the areas it has infested; New Englanders especially remember the spring of 1981, when the chomping of gypsy moth caterpillars kept them awake at night and swarms of the insects rendered pools and parks unusable. Every year, as the insect extends its range and more communities see their trees inexplicably stripped, antichemical sentiments often turn to demands to "Spray now! With anything!" long after treatment would be useful. And yet, a few miles from huge infestations, forests can be completely untouched.
Strong young trees can withstand several years of major defoliation by the gypsy moth. However, older, weak, or drought-stressed trees can be killed by a single defoliation, and surviving trees are more susceptible to disease and parasitism. Since many high-value ornamental shade trees are mature, they are particularly vulnerable to the gypsy moth.
Areas infested with the gypsy moth can be sprayed with either man-made or natural insecticides. However, these are expensive and not always desirable, and the location of likely outbreaks is difficult to predict. Scientists from the U.S. government, academia, and industry are trying to understand the insect and develop effective and environmentally sound methods of control. More effective biological insecticides, the introduction of foreign parasites, and male sterilization are all options being studied. Researchers are also seeking to improve methods for detecting the infestation and for preventing forest stands from losing value due to tree mortality. In fiscal year 1989, the U.S.Congress appropriated $15.1 million to fight the war against the gypsy moth, $5.7 million of which was allocated for research.
Origin And Spread
Ironically, the moth that is the focus of so much effort by scientists was introduced to the United States by another scientist. In 1869, naturalist Leopold Trouvelot imported gypsy moths from France to try to cross the insect with silkworms to develop a breed of silk producers capable of existing in a cool climate. During a storm, several of the moths escaped from his home in suburban Boston. Mindful of the damage the gypsy moth caused in Europe, Trouvelot reported the escape immediately, but was not able to
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