“Do mosquitoes migrate?”

Asian tiger mosquito
At last! A picture of an Asian Tiger Mosquito that doesn’t make me want to scratch! (Image by Ronnie Pitman / nikkorsnapper via Flickr)

Mosquito Week continues with a look at why we get a break from those pesky biters (at least in the Northeast) in the winter.

In comforting The Four-Year-Old who is still struggling with itchy bites even though it’s almost Thanksgiving, I happened to mention that at least she wouldn’t have to deal with mosquitoes for much longer.

The Four-Year-Old naturally wanted to know why, and when I told her, she asked: “Mommyo, if mosquitoes don’t do well in the cold, how do they come back in the spring and the summer? Do they migrate?”

Technically, mosquitoes do not migrate. Some have gotten caught up in the wind, ending up some 75 miles away from their breeding ground. They can also hitch a ride across continents from unsuspecting humans. The Asian tiger mosquito, which now thrives in 21 states, was first imported to the U.S. from Japan in a pile of scrap tires.  Most, though, live within a mile or two of their breeding grounds their entire life.

So, if they don’t migrate, how do they survive the winter? I’m sure it will come as no surprise to most of you that most mosquitoes don’t. Male mosquitoes typically only live a week or two. Females live longer, up to a month. Not long enough to  survive a winter, right?

For a long time I had assumed that the cold killed all the adult mosquitoes off, leaving only the mosquito eggs to launch the next spring’s crop. Imagine my surprise (and subsequent itchiness) when I learned that female mosquitoes can make it through the winter in relatively temperate areas. We think they’re gone because they no longer come out to feed when the temperature drops. But in fact, those wily females may simply be sheltering in old logs and animal homes waiting for the worst of the cold to pass, so that they can emerge unscathed (and hungry) to lay one last batch of eggs in the spring.


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