Conservation Connection: Does a hard winter really kill bugs?

(KPLR) - You’ve probably heard it before.  Every time we have a hard winter full of single-digit temperatures like this one, there’s a lot of talk about the extreme cold killing off ticks and mosquitos and other pests.  But are hopes for a pest-free summer based on reality or myth?  Natural History Biologist Mike Arduser talks with John Fuller about the reality.

Q.  So let’s cut to the chase . . . is it true?

  • For the most part . . . no
  • These creatures have been around much longer and survived much worse conditions than humans have
  • They have adapted ways to survive
  • Winters have always been cold . . . and if these critters couldn’t adapt, they’d have been gone long ago
  • Many insects need far colder temperatures to die off then even we’re experiencing now
    • For example, studies of the emerald ash borersuggest that temperatures must plummet to minus 30 degrees in order to achieve widespread mortality


Q.  How do these insects survive?

  • They normally  go into diapause and are dormant this time of year
  • In some species, the previous generation die off by the start of winter, and the next generation doesn’t emerge until spring
  • Parasites like fleas can lay eggs onmammals, which keeps them warm, to preserve them until spring
  • Many North American insects have strategies to prevent fatal ice crystals from forming in their fluids:
    • Some find a completely dry place to overwinter where ice crystallization cannot occur
    • Some also completely empty their gut before winter to prevent ice crystallization forming inside the body
    • Others actually produce glycerol or proteins in their bodies during winter months that act as “anti-freeze”
    • Heavy snows can actually benefit some insects like mosquitos.  Large amounts of snow melt can result in wetter springs . . . and create more breeding areas for mosquitos


Q. So is there any way the cold can affect these creatures?

  • Possibly . . . it’s more a matter of timing
  • If it warms up enough for the insects come out of diapause, then an abnormal late freeze in spring can cause high mortality
  • Very similar to garden plants and flowers . . . they don’t die off because of a cold winter since they’re dormant.  But if a late freeze hits after they’ve flowered or leafed out, they could die


Q.  So what’s the best defense against ticks and mosquitos this spring?

  • Cover your skin and use bug spray!

Suggest a correction


  • Dana

    Duh, don’t take an Einstein to figure that out! What a waste of a minute out of my life, I’ll never get back, lol!

  • don horst

    So what do you think happens to the armadillo population in Jefferson county Missouri? for the last few years they have really moved into the festus area. I was hoping that the cold would affect them and give some relief to my yard.

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