As temperatures plummet into the single digits, people will often seek any silver lining in the cold, cold days and nights.
A common theory is that bitter cold winters lead to fewer bugs — pests like gnats and mosquitoes — come summertime.
But Tim Gibb, a professor of entomology at Purdue University says that’s nothing more than an old wive’s tale.
“We hear that all the time,” he said with a chuckle. “But if it were really true, that a hard freeze kills off bugs and pests, then wouldn’t there be some years we didn’t have any at all?
“Because we always have hard freezes,” Gibb said. “It’s just not true.”
Gibb said the real truth about bugs and wintertime is quite the contrary.
Gnats and mosquitos are ectothermic, meaning their bodies adapt to the cold weather quite well. Bugs actually enter a cold-appropriate physiological state in which their bodies don’t form ice crystals, a process that protects them from the bitter cold weather.
“In almost every case,” Gibb said, “insects have found a way around a hard freeze. If an insect can keep from forming ice crystals in its body, it can undergo real, subzero weather.”
What pesky insects can’t adapt to, however, is a winter that brings with it a “roller coaster” of temperatures, a trend similar to what the area has experienced so far this winter.
“What really causes them trouble is when we get into a pattern of seeing low temperatures and then coming out of them only to plunge back into (the single digits) again,” Gibb said. “Physiologically, an insect is going to have real difficulty in dealing with that. They just have to change too much.
“They can’t adapt to the roller coaster,” Gibb said, “and if we have a lot of that, then insect populations do begin to suffer.”
That said, ups and downs in temperatures experienced so far this winter haven’t been extreme enough — at least not yet — to harm pest populations.
What does, without a doubt, affect the number of bugs seen in the hot summer months, however, is the amount of precipitation that falls in the springtime, Gibb said.
“The more rain we see in the spring means (a greater) potential for mosquitoes and gnats,” Gibb said. “In the cold, bugs, their larvae and eggs, they’re hearty. They actually do really well.
“But in the springtime, once the warmer weather and water gets to them, that’s when they hatch and we see those huge populations.
“So a lot more goes into bug populations besides what happens in the winter months,” he said. “It’s something we just won’t know more about until springtime.”
Jenny McNeece
Vincennes Sun-Commercial
