Harvest Desk
12:41 pm
Wed February 12, 2014

Harsh Winter Freezing Out Some Crop-Devouring Pests

Western corn rootworm beetles munch on a corn stalk
Credit Purdue University Extension

Despite what they may be thinking now, Midwest grain farmers and backyard gardeners alike may be thankful for the recent arctic temperatures before 2014 is out.

That’s because soil that’s frozen solid from weeks of below average temperatures isn’t exactly a cozy spot for hibernating insects that feed on crops as soon as the spring thaw comes.

Entomologist Michael Gray at the University of Illinois specializes in tracking pests like the corn rootworm, a bug that farmers particularly detest.  Research has shown rootworms are resistant to some Bt corn, a biotech hybrid that is supposed to keep insect larvae from chewing up roots. 

Gray says that he’s always been impressed by how superbly adapted some insects are to surviving harsh winter conditions, but those that hibernate as baby beetles (grubs) in the soil – such as the flower and leaf-devouring Japanese beetle – are vulnerable.

listen to Harvest Desk interview with UIUC Prof. Michael Gray

“We’ve had the soil frozen much more deeply than we’ve seen in many years,” Gray said. “I do think this winter will take its toll and increase the level of mortality on some of those insects.”

Still, Gray expects farmers and gardeners will see some survivors in 2014.

Due to their potential for environmental hazard, Gray suggests pesticide treatments be used “judiciously,” rather than as a form of “insurance”.  

For example, Gray last year advised corn and soybean growers to carefully monitor the density of rootworm beetle populations in their fields. Paying attention to the density of the pests gives farmers an idea about egg laying and the level of infestation they might see in 2014.

Even after the especially chilly winter, growers aren’t out of the woods. Not all pests stick around to risk the freezing winters of the Midwest. Several species of crop-chewing insects – from the corn ear worm to corn leaf aphids - migrate from as far as Mexico and won’t be impacted by the “polar vortex” that has slammed the upper half of North America. 

And then, of course, there are some pesky insects that may not devour fields of crops, but can make a mess in your home as they try to survive the winter. 

“Some move indoors,” Gray added. “We’re all familiar with those multi-colored Asian lady beetles, which try to get in our attics, garages, what-have-you, to over-winter.“

You can’t blame them for trying to get indoors in this weather.

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