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  • Unlike us lucky endotherms, insects can’t regulate their own body temperatures.

  • Theyre at the mercy of their environment.

  • So when the cold winter arrives, how do they keep from freezing?

  • They basically have three choices. They can leave for warmer places, they can wait it out,

  • or they can kick the bucket.

  • Just like some birds, there are a few insects, like dragonflies or butterflies, that fly south for the winter.

  • The most famous of these has got to be the monarch butterfly.

  • There’s a population that normally lives in the northern U.S. and Canada, but spends

  • the winter in the balmy mountain forests of Mexico.

  • Of course, many insects have shorter lives than birds.

  • So, a special migratory generation of the monarchs flies south thousands of miles to Mexico without

  • reproducing, but it takes four or five generations to make the trip back north.

  • If an insect can't leave when winter arrives, option number two is to hunker down and wait

  • for things to warm up again.

  • Insects like ladybugs, emerald ash borers, and mourning cloak butterflies burrow into

  • soil or leaf litter for warmth.

  • There, these adult insects enter a kind of

  • hibernation called diapause, thanks to hormones triggered by the shorter days

  • and cooler temperatures of autumn.

  • Their metabolic rates drop dramatically, so they don’t need as much food.

  • And some species even pump their tissues full of alcohols that act as a natural antifreeze.

  • Basically, these chemicals lower the freezing point inside their cells, which prevents damaging

  • ice crystals from forming.

  • Now, plenty of insects, like crickets and grasshoppers, just throw in the towel when

  • the temperature drops.

  • The adults die off after reproducing in the fall, and the next generation spends the winter

  • as dormant eggs or larvae.

  • These babies are usually pretty well-equipped for survival: Eggs and larvae can enter diapause

  • just like adults can, and some get extra help from their doomed parents.

  • Praying mantises, for example, envelop their eggs in a foam-like protective protein case.

  • These days, climate change is messing with the overwintering strategies of some insects.

  • And it’s even letting some less cold-tolerant species venture farther north.

  • Which... usually isn’t so great.

  • Like, thanks to milder winters, the mountain pine beetle has been expanding its range and

  • killing vast swaths of trees in western North America.

  • So when it gets cold out, do you put on a coat and keep trucking?

  • Curl up under a blanket with hot chocolate until spring?

  • Or do you make like a monarch and head for the tropics?

  • Whatever your way of dealing, spare a thought for the insects that make it work without

  • central heatingjust with some clever adaptations.

  • Thanks to Patreon patron Zach Lerman for asking, and thanks to all of our patrons who keep

  • these answers coming.

  • If you'd like to submit questions to be answered,

  • go to patreon.com/scishow

  • And don't forget to go to youtube.com/scishow and subscribe!

Unlike us lucky endotherms, insects can’t regulate their own body temperatures.

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昆虫はどうやって冬を乗り切るのか? (How Do Insects Survive the Winter?)

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    g2 に公開 2021 年 01 月 14 日
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