During the recent cold snap, it has been somewhat comforting to believe that although we are uncomfortable, the cold weather will head off a repeat of last summer’s invasion of Japanese beetles.
Alas, it’s a lie.
“Bottom line is zero, below zero, doesn’t make much difference to insect populations,” Donald Lewis, professor of entomology at Iowa State University, tells the Omaha Herald.
All of the beetles who invaded are gone now and next year’s beetles are grubs, currently embedded six inches in the ground, protected by a layer of snow and the outrageousness of evolution.
Even when the ground freezes, he said, the grubs are protected from ice formation by a small amount of antifreeze in their bodies.
Some grubs die every year, but enough of them survive winter to start the life cycle again, he said.
Snow on the ground just provides the bugs an extra layer of insulation.
The University of Minnesota Extension Service says the grubs could be down as much as a foot into the ground by now.
What would work is temperatures in the 50s, leading the grubs to move higher in the ground, followed by another deep freeze, killing them before they can burrow deeper.
The good news is the Emerald Ash Borer is hiding just under the bark of your ash tree and bark is not a good insulator. The bad news, according to the University of Wisconsin Extension Service, is it’ll take temperatures -30 or lower to kill them.