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Cold Snaps & Invasive Insects

626-EmeraldAshBorer_lg - UNH EXTENSION(Our recent plummeting temperatures in the Northeast convinced me to re-post this in an effort to see a silver lining.)

There can be a plus side to the sub-zero temperatures New England experiences in winter – the cold weather may well decrease the number of invasive pests we have. An example of this is the Hemlock Woolly Adelgid (the aphid-like introduced insect decimating the eastern hemlock population) which succumbs at 4 or 5 degrees F. However, some insects are not fazed by the cold until it dips way below zero. At -20 F., roughly half of the Emerald Ash Borer larvae (an invasive beetle that is highly destructive to ash trees) overwintering in trees will die. Once the temperature reaches -30 F., there’s a 90 percent mortality rate. Bed Bugs face instant death at -22 degrees F., but it takes 24 hours to kill them at -11 degrees F. and 72 hours to kill them at 0 degrees F.

Unfortunately, once an invasive insect establishes itself, even if its numbers go way down for whatever reason, it usually rebounds in several years’ time. Some invertebrates are not affected by the cold temperatures. The Black-legged (Deer) Ticks that reside on moose, deer, mice, birds and other hosts can withstand sub-zero temperatures as they have the warmth of their hosts’ bodies to keep them warm. In order for ticks to succumb to the cold, the frigid air has to last until May, when the fertilized female ticks fall off their hosts to lay their eggs. (photo – emerald ash borer, public domain image)

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7 responses

  1. carol stanley

    you are right! good to have something positive when its this cold! thanks.

    January 9, 2015 at 1:22 pm

  2. Cecelia Blair

    The severe cold also cuts down on the numbers of invasive humans in Northern New England. A graph of the population by latitude or winter temperature zone would be telling!

    January 9, 2015 at 2:43 pm

  3. Cecelia

    Mary, here is one.

    January 9, 2015 at 11:03 pm

  4. And I would think that there are beneficial insects that are harmed by low temperatures.

    January 10, 2015 at 11:23 am

  5. Diane

    This is a very informative article. I so wish there were natural ways to kill off tree borers and of course ticks. Doubt if we in SE,PA will see temperatures frigid enough for the emerald ash borer.

    January 10, 2015 at 2:58 pm

  6. A silver lining – beauty of ice and snow is the reward we generally think of, but insect mortality is a good one.

    January 10, 2015 at 10:34 pm

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