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To protect plants, experts say to catch tent caterpillars soon

Cynthia Schuster

Wisconsin Public Radio

Eastern tent caterpillars are making their annual appearance in Wisconsin as buds begin to open and reveal the first leaves of spring — and if not controlled early, the crawling creatures can wreak havoc on plants.

“So often, when I was running the diagnostic lab, I’d get the call or specimens a week or two too late for doing anything of any significance,” said Phil Pellitteri, the former director of the University of Wisconsin Insect Diagnostic Laboratory in Madison.

Pellitteri added that by acting right away, the caterpillars can be dealt with rather easily — by hand-crushing them and scraping them off the foliage.

“If you let them go three weeks from now, then they’re going to be big and crawling all over the plant and be more difficult to deal with,” he said.

Pellitteri advised against what he calls “revenge treatments” — any kind of pest control that occurs after that initial three-to-four week window. It might end up harming the plants on which the caterpillars are feeding, and according to Pellitteri, while “it makes you feel better … you’re not going to influence next year’s population. There’s just too many other things going on.”

Caterpillars that make it through the spring will appear as dark brown, rusty-colored moths around July.