Warm weather brings earlier, not more, insects

You probably have been bothered by more than the usual number of pesky insects in the past week, given it’s still only mid-March.

But the good news is that it doesn’t mean the insect population will be any greater than normal this spring and summer, according to a University of Illinois Extension entomologist.

“Generally, the winter has had no effect on the insect population,” entomologist Phil Nixon said.

Because of the past week’s record warmth, the insect population has been coming out of hibernation much faster than usual, Nixon said.

It usually takes about three or four weeks of gradually rising temperatures for all the hibernating insects to emerge. But when temperatures abruptly leapt from the 40s to the 80s last week, it brought virtually all insects out at once, Nixon said.

Those first mosquitoes you may have encountered are adults that stayed dormant through the winter, he said. Fortunately, while you may have suffered bites already, there’s no risk of West Nile virus as the virus needs a longer period of warmer weather to be active, Nixon added.

So how can those little delicate mosquitoes make it through even colder winters than the one we had? They’re able to reduce the liquid content in their bodies and produce long-chain alcohols that effectively raise the freezing point of their blood, Nixon said.

Though some people have been anticipating a greater insect population because of the warm winter, it’s actually the spring weather yet to come that determines how well insects will thrive this year.

A cool, damp spring makes insects more vulnerable to fungal diseases and increases their mortality rates, Nixon said.

In comparison, the winter gives insects very little to worry about. They can hibernate comfortably in temperatures ranging from 50 degrees Fahrenheit all the way down to 10 below, so the human perception of a “warm” winter with temperatures in the upper 30s and 40s makes little difference to dormant insects.

Among the species that go through the winter as adults, all have their own particular ways of going about it, Nixon said. Mourning Cloak butterflies, for instance, fold themselves up and tuck themselves away under loose edges of tree bark.

Though mosquitoes are one parasitic insect already off to a flying start this year, the warm weather should not have equally benefited that bane of cats and dogs — fleas.

“It’s probably a tad early for fleas to emerge,” Nixon said.

The so-called cat flea, which afflicts both types of household pet, evolved in conjunction with the big cats of Africa and requires a much longer period of warm weather than we’ve seen so far this year to thrive.

Fleas can survive through the winter with the assistance of a mostly indoor cat or dog, but they’re not hardy enough to make it through the cold months without a host, Nixon said.

Catherine Howes, office manager at Golf Rose Animal Hospital in Schaumburg, agreed. But as the seasonal return of fleas is still on the horizon, this is the time for pet owners to think about preventive treatment, she said.

“I think we’ll be seeing them soon,” Howes said. “The time to worry is now.”