(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!