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Cold Snaps & Hardy Invertebrates

1-14-14 TICK IMG_0528As you may have heard, there could be a plus side to the sub-zero temperatures we’re experiencing this winter – the cold weather may well decrease the number of invasive pests we have. For example, the Hemlock Woolly Adelgid (the aphid-like introduced insect decimating the Eastern Hemlock population) succumbs at 4 or 5 degrees F. However, other insects aren’t phased 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.

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6 responses

  1. Louise Garfield

    I had not realized that female ticks could stay on a host all winter as I belived that once the tick was full of blood, it fell off.

    January 14, 2014 at 2:31 pm

    • Hi Louise,
      I have not observed this first hand, but have read in more than one source that mated females spend the winter on their hosts…but your point is well taken! Perhaps they limit their feeding in the winter? But they must need nutrients to form their eggs. A mystery…

      January 14, 2014 at 3:01 pm

  2. Kathie Fiveash

    Here is an interesting excerpt from a book called White as a Ghost: Winter Ticks & Moose
    By Bill Samuel. It’s not about deer ticks, though, but about a one-host tick called the winter tick (Dermacentor albipictus) I’d never heard of before. The graph is fascinating.

    You can also google winter ticks, which is also interesting.

    January 14, 2014 at 5:38 pm

    • Looks fascinating! I was aware of the winter tick’s impact on moose, but I didn’t know that it only used moose as hosts. Thank you, Kathie!

      January 14, 2014 at 8:43 pm

  3. Ruth Sylvester

    >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.
    I wonder what the physiology or chemistry or whatever it would be of this is. I.e., what’s going on with cells exploding or chemicals doing something that changes over some hours.

    January 15, 2014 at 1:59 pm

    • Yes, I wonder, too, Ruth. Afraid my knowledge is too limited to explain this phenomenon.

      January 15, 2014 at 3:02 pm

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