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Snow Fleas

Hypogastrura nivicola


Snow fleas are not a type of flea. Neither are they insects. Rather, they are arthropods that belong to the class Entognatha. During most of the year they live in the soil and leaf litter where they consume fungi and decaying vegetation. They are actually crucial decomposers! On warm winter days, they often appear on the surface of the snow and since they are tiny (~1mm) like fleas, they are referred to as "snow fleas". Their migrations from the soil/leaf litter to the snow may be triggered by overcrowding or lack of food. They do not have wings, but instead have tail-like projections called furcula, which are held like a spring on the bottom of their abdomens. When a snow flea wants to move, the furcula springs down and catapults the snow flea as far as 100 times its body length! Furthermore, snow fleas in the genus Hypogastrura have three anal sacs, which they evert just before jumping. These sacs are thought to serve as sticky air bags, which prevent the snow fleas from bouncing around randomly when it lands. Pretty amazing biology!


I spotted thousands of these springtails in the woods - they were all over rocks, rotting wood, trees, and leaf litter. Everything was very wet from snow melt and recent rain. Snow fleas are one of the most numerous land animals, with several hundred thousand possibly living in one cubic yard, but it was still a surprise to see as many as I did!


I'm wondering if food sources for these creatures are scarce right now, or if they normally engage in cannibalism because I spotted several groups clustered together eating each other (photos 1 and 3), thus exhibiting a type of cannibalism called Intratrophic Predation.

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Leuba Ridgway
Leuba Ridgway 3 years ago

Great photos Christine. Interesting information about the anal sacs - just visualising the little critters without them !

maplemoth662 3 years ago

Beautiful photos....interesting photos....

SukanyaDatta 3 years ago

How interesting!

Christine Y.
Christine Y. 3 years ago

Thank you for the nomination!

AshleyT 3 years ago

Your spotting has been nominated for the Spotting of the Week. The winner will be chosen by the Project Noah Rangers based on a combination of factors including: uniqueness of the shot, status of the organism (for example, rare or endangered), quality of the information provided in the habitat and description sections. There is a subjective element, of course; the spotting with the highest number of Ranger votes is chosen. Congratulations on being nominated!

Christine Y.
Christine Y. 3 years ago

You're welcome and thanks Mark! It was amazing to see them covering literally every surface. I initially spotted them because I was looking for a rock to rest on, but couldn't find one lest I squish these little buggers.

Mark Ridgway
Mark Ridgway 3 years ago

Fascinating. Great info. Thanks.

Christine Y.
Spotted by
Christine Y.

Connecticut, USA

Spotted on Feb 24, 2018
Submitted on Feb 25, 2018

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