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Snow Flies Appearing

1-29-18 snow fly IMG_9481It always comes as a surprise to see tiny creatures moving nimbly over the surface of the snow. However, there are quite a few insects and spiders that do, thanks to the glycerol that they produce in their body fluids that keep them from freezing. The Snow Fly (Chionea sp.) is a type of wingless crane fly.  Most likely its lack of wings is due to the fact that at sub-freezing temperatures it would be very hard to generate enough energy for maintaining flight muscles. They (along with other flies, mosquitoes and gnats) do have two vestigial wings called halteres, the little knobs on the fly’s thorax. They inform true flies about the rotation of their body during flight, and are thought to act as sensory organs for the flightless Snow Flies.

Throughout most of the year Snow Flies can be found in leaf litter, but come winter the adults emerge, mate and lay up to 200 eggs. The lack of predators such as dragonflies and most insect-eating birds makes winter a relatively safe time for Snow Flies to be out and about. Their life span is about two months, during which time they drink by pressing their proboscis against the snow, but they don’t eat.   (Snow Fly in photograph is a female, measuring less than ½”.)

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12 responses

  1. Ruth Sylvester

    What an amazing photograph!

    January 29, 2018 at 7:54 am

  2. Jo

    Are these related to ‘snow fleas’? I’ve seen tiny critters, like specks of pepper, moving on the snow surface (not recently).

    January 29, 2018 at 8:28 am

    • Related, but not closely. They are both in the group Hexapoda (which contains the Insecta) but snow fleas are not classified as insects.

      January 29, 2018 at 5:33 pm

  3. Jo

    Oh, I just followed one of your tags tho your entry on Snow Scorpionflies, which seems to describe what I’ve seen.

    January 29, 2018 at 8:32 am

  4. Could this be the same thing as a stink bug?

    Sent from my iPhone 7 Plus Brandt Denniston (603)496-5690

    January 29, 2018 at 9:01 am

    • Many insects are referred to as stink bugs, none of which are active in winter, at least as far as I know. Snow flies and stink bugs are both insects, but that’s about as close as they come to being related.

      January 29, 2018 at 5:35 pm

  5. Nice to know something about these guys I’ve been seeing for years and wondering about.. Thanks!

    January 29, 2018 at 9:57 am

  6. What a great adaptation, for an insect to be able to be active in the winter, when there are very few insectivores around! I love the way every niche seems to have its occupants.
    So is it that these critters don’t eat as adults – they’ll just die after mating and laying their eggs? Do they go back down to the leaf litter to lay the eggs? Do they start out as larvae, hanging out in the leaf litter, in the spring?

    January 29, 2018 at 10:12 am

  7. Marilyn

    Somewhere in the life process they must ingest nutrition, other than the adult “drinking” water … ?

    January 29, 2018 at 2:43 pm

    • Not from what I’m told and have read, Marilyn. Two months does seem like a very long time to exist without any food – most moths that don’t eat have a much shorter lifespan. But according to entomologists, snow flies don’t eat and do live that long!

      January 29, 2018 at 4:41 pm

  8. Jane Crandell

    Hello Mary, As a member of the Cornish Garden Club I would love to suggest you as a future speaker. I read recently that you gave a talk to the New London club. Do you have a list of topics and what is your fee? My husband and I recently retired back to New England after 26 years living in Louisiana and enjoy your postings that put us back in touch with all things hereabouts. The accompanying photos are wonderful also. Thanks for educating us anew! Best warm regards, Jane

    Jane Crandell 32 Parsonage Road Cornish, NH 03745 (603) 675-2037 (978) 493-4865 cell Mail: PO Box 324 Cornish Flat, NH 03746


    January 29, 2018 at 5:03 pm

    • Hi Jane,
      How nice to hear from you. If you send me your email address (mine is mholland@vermontel. net) I will get back to you about programs! Many thanks!

      January 29, 2018 at 7:23 pm

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