Moths

Moths

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The preliminary figures, Mr. Kline stressed, indicate only areas “moderately to severely” defoliated. Spots that were only lightly affected would not be included in the preliminary survey, he said.

A more detailed study of the affected areas will be available late this year, after high-level aerial photos are compared with low-altitude mapping done by survey crews. Then, as a final check, areas which remain questionable are surveyed from the ground to determine the cause of the defoliation.

A total of 5,470 acres was included in the government’s Appalachian Integrated Pest Management Program spraying, all in the southern one-third of the county.

Of that area, the 640 acres sprayed with Dimilin seemed to yield the best results, Mr. Kline said. “The Dimilin made a big difference.”

Another 4,675 acres was sprayed with Bt (bacillus thuringienses), a biological growth control. That was less successful in controlling the caterpillars, the forester reported. He speculated that the heavy rainfall in the days right after the spraying reduced its effectiveness.

And, he added, Bt is more effective at low levels of infestation. “The population was just too big and healthy . . . When you get the numbers involved in a peak outbreak, there are just too many caterpillars.”

Throughout Virginia, according to State Forester James Gamer, the caterpillars infested more than 500.000 acres this year. Last year, the total defoliation was only about 200.000 acres.

The areas hardest hit, he said, were Rappahannock, Page, Madison, Shenandoah and Rockingham counties. But affected forests stretch from the West Virginia line to the Eastern Shore, and from the Northern Virginia suburbs down the Blue Ridge Mountains to Amherst and Rockbridge counties.

Mr. Gamer said he expects the affected area to increase dramatically again next year as the caterpil