2008-05-17 / Front Page


Biologists are expecting a banner year for forest-wrecking caterpillars, which can be found wrapped in webbing in thousands of area trees this month.

At this point, the eastern tent caterpillar appears to be the main villain in northcentral Pennsylvania.

Eggs laid last year hatched over the past month, and the aggressive insects have begun spinning their tent-like shelters.

In some areas they have already begun stripping the emerging leaves from hardwoods- especially cherry, crab apple and apple trees.

One saving grace of the early attack is the fact that although the insects can completely defoliate a tree in a relatively short time, the trees will often refoliate.

Trees are very rarely killed by defoliation from this insect. They can, however, be damaged by repeated defoliations in successive years.

Tree mortality can be more of a threat if caterpillar defoliation is joined by other stresses, such as drought, according to the Pa. Bureau of Forestry.

The insects go through several stages of development as caterpillars as they grow and, by midsummer, enter the pupal or cocoon stage. They emerge, usually in late July, as reddish-brown moths similar in appearance to gypsy moths.

State officials recommend control of the caterpillars by Bt, a biological pesticide that consists of a bacteria. The larva must eat the bacterial insecticide that has been sprayed on the leaves in order for it to be effective.

Treatment with chemical insecticides or by burning is not recommended by the Forestry Bureau, due to the potential for harmful side effects to more welcomed creatures.

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