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small stands of trees, he said, or individual trees in yards. Small oaks can be treated with a household sprayer, and some tree surgeons have power apparatus which will reach the crowns of larger trees.
For timber stands, there are companies which offer aerial spraying, although depending on the weather and the severity of the infestation it is of questionable effectiveness.
At outbreak levels, however, Mr. Kline said, “spraying is the most effective control.”
Dimilin, a pesticide which interferes with the caterpillar’s growth pattern, and Bt, a biological control, are the two chemicals most frequently used for gypsy moth eradication. Bt, Mr. Kline said, is most effective for low-level outbreaks. Dimilin, “a little more toxic but still safe,” is used by the Department of Agriculture and the Virginia Department of Agriculture and Consumer Services in their spray programs.
Mr. Kline stressed, however, that it is important that people recognize that the gypsy moth, like other pests, is subject to periodic peaks and valleys of population.
The severe infestations seen during the last several years will not be an annual occurrence. The population will die back after a few years and the defoliation will be much less severe. The most vulnerable oaks are those which are already stressed, he said, whether because
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