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Snow Fleas Are Peppering The Snow

Duringwarming temperatures at this time of year the snow can be covered with tiny black specks (1 – 2 mm long), resembling pepper sprinkled on the snow.  If you watch them for a period of time, you’ll see that these specks move — leap, in fact — a distance often several times their body length.  These moving specks are called snow fleas, a species of springtail, not a type of flea. For that matter, they are not insects, but close relatives to arthropods, specifically crustaceans. During most of the year snow fleas live in the soil and leaf litter, consuming fungi, algae and decaying organic matter. On warm winter days they appear on the surface of the snow, often at the base of trees or in track indentations. 

Their acrobatic prowess is achieved not with wings, which they lack, but with two tail-like spring projections, or furcula, which are held like a spring against the bottom of their abdomen by a kind of latch. When the snow flea wants to move, the latch is released and the furcula springs downward, catapulting the snowflea as far as 100 times its body length.

Snowfleas in the genus Hypogastrura possess three pinkish anal sacs which are usually located inside the snowflea, hidden from view. Just before jumping the snowflea everts these sacs from its anus. Their function has not been confirmed, but many biologists believe they serve as a sticky safety bag which prevents the snowflea from bouncing around when it lands.

The anti-freeze protein that allows snow fleas to be active at colder temperatures than insects is being studied in the hopes that they can be used to better store transplant organs.

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6 responses

  1. Thanks for all the interesting information you included about how snow fleas do what they do, Mary. I remember the first time I noticed these critters remarkably hopping around in the snow in late winter – before there was an Internet to research them. I was mystified, till someone who’d been around longer than I told me that they were called “snow fleas.” It was quite a few years later before I heard them called “springtails.” This was enlightening in that it gave me a sense of how they propelled themselves so impressively. But now I know about the “latch” and the “anal sacs” – my goodness – the marvels of useful adaptations!

    March 3, 2023 at 9:59 am

  2. A favorite late winter moment for my grandchild and I. The great mystery for us, which my research and talking to insect-specialist colleagues hasn’t answered, is how do they get into tracks and impressions out in the open that neither go deep to the ground or are near to tree trunks or any littered debris. Wind, maybe?

    March 3, 2023 at 10:56 am

  3. Alice

    Such interesting little jumpers.

    March 3, 2023 at 11:01 am

  4. Jan Beckert

    You might enjoy this entertaining site:

    March 5, 2023 at 10:40 am

  5. Louise

    I was cross country skiing yesterday in a great open meadow, and the snow fleas were moving about. I noticed the majority were heading west-northwest in the early afternoon, and was “curious”. I hope the ones that were in my path survived the impact of the skis !

    March 6, 2023 at 8:57 am

  6. Louise

    Now that I read the article again, I am not certain I was observing snow fleas, as they were not jumping, but skittering on little legs–what could this out creature be?

    March 6, 2023 at 8:58 am

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