Climate change opens door to new forest pests

By Jessica Batanian

The mimosa webworm was nowhere to be found on honeylocust trees at Michigan State University 20 years ago.

But within the past decade, warming temperatures made the East Lansing, Michigan campus an appealing home for this destructive bug.

“It was the canary in the coal mine,” said Deb McCullough, an entomologist at the university who witnessed the honeylocust trees disappear from campus as temperatures warmed and the mimosa webworm moved north into Michigan.

It’s a phenomenon not confined to webworms and honeylocust trees as the Earth’s temperature rises and the variability of climate increases.

Climate change will increase the frequency of droughts, increase the severity of snow/rain storms and make frosts occur later, said Sophan Chhin, assistant professor in the department of forestry at Michigan State University. As climate changes and growing seasons are interrupted by drought and frost, trees are preoccupied with regaining their strength and become more vulnerable to insects and disease.

The hemlock woolly adelgid is another insect of concern for the Great Lakes region. It attacks a type of pine tree called hemlock and has not yet breached the northern parts of Michigan and Wisconsin because of colder temperatures.

“Currently, Wisconsin is a little too cold but that may become less of a case with climate change,” said Ken Raffa, a professor in the department of entomology at the University of Wisconsin – Madison. Insects are moving farther north than they ever have in the past, he said.

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