Winter still bugging us: Pests can take extreme cold

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February 17, 2014

A long, frigid winter in the Chippewa Valley will not necessarily mean fewer bugs this summer.

UW-Extension entomologist Phil Pellitteri said some people have speculated that this winter’s unusually cold weather will result in a summer with fewer pesky bugs.

But Pellitteri said there are 25,000 species of insect in Wisconsin and they have evolved to live through harsh Wisconsin weather. For instance, extreme cold doesn’t seem to adversely affect mosquitoes, he said.

Spring weather can have a bigger effect on insects. If the weather warms and insects hatch prematurely, a return to freezing temperatures will hurt their numbers, he said.

“If their eggs hatch and they wake up, then they’re in a more vulnerable state,” he said.

Still in the midst of February with snowfall throughout the weekend and Monday, Pellitteri didn’t want to speculate on this winter’s effects on local bugs.

“If I’m going to make a prediction, I feel a lot more confident in the middle of May,” he said.

Emerald ash borers

One insect pest that might be affected by the cold is the emerald ash borer, an invasive bug from Asia that has been spreading throughout Wisconsin and the Midwest. The creatures damage and eventually kill ash trees.

Temperatures of 30 below or lower kill more than 90 percent of borers while temperatures of 20 below kill 20 or 30 percent, Pellitteri said.

Scientists have introduced parasites to control emerald ash borers, but those parasites also could be harmed by cold weather, Pellitteri said.

“We’re extremely nervous that the parasites aren’t going to survive the winter,” he said.


Scientists are unsure how this year’s arctic winter will impact deer ticks, which carry Lyme disease, said K.T. Gallagher, environmental health supervisor with the Eau Claire City-County Health Department.

The ticks’ primary source of food, deer mice, appear good at surviving hard winters, Gallagher said. Even if the winter does reduce the mice, which in turn curbs the number of ticks with Lyme disease, scientists won’t know until 2015, when the ticks that feed on this summer’s crop of deer mice are adults, she said.

Susan Paskewitz, a UW-Madison entomologist, said a Wisconsin winter hasn’t been this cold for this long since 1980, during the early phase of deer tick expansion and Lyme disease emergence in the state.

“My guess is that the ticks are tucked in under the snow and may be doing OK, but we’ll have to wait until spring samples to be sure,” she said.

Deer also are a host of the ticks, and if this winter adversely impacts the deer population, it could reduce the tick population, Gallagher said.


Pellitteri said he the cold winter is probably more of an issue for horticulturists and landscapers.

With recent mild winters, more state residents have been trying to grow plants and trees from more southern climates, he said.

“I’ve got a neighbor who’s trying to grow peaches,” he said. “I’ve got a feeling that tree is going to be toast.”

Knight can be reached at 715-830-5835, 800-236-7077 or