File this under the heading “silver linings”: the extreme cold that our region experienced over New Year’s could slow the expansion of invasive insects here.
For several days in late December and early January, temperatures stayed well below zero. State entomologist Alan Graham says that can affect insects that over-winter in Vermont. He says the populations of pests like the wooly adelgid could be slightly reduced by the extreme cold. “The Hemlock wooly adelgid can’t stand really cold temperatures," says Graham. "We may get a setback in Hemlock wooly adelgid population in southern Vermont.”
Another destructive invasive insect that Vermonters haven’t found here yet is the emerald ash borer. That insect has been spreading north, but the cold might mitigate its population as well. "It depends on how many days at sub-zero temperatures the climate remains," says Graham, "so that the cold temperature can reach into the core of the tree.”
Unfortunately, Graham says that ticks are able to survive cold just fine under the snow cover or on host mammals like small rodents. He cautions that the overall effects of this year’s cold on insects will not be known till summer when the insect populations can be accurately measured.
