Snow-fleas (Hypogastrura nivicola, Order Collembola, Class Insecta) were first seen on Monday, March 1st and have been common on snow and in puddles during the week. These animals are not true fleas, but are harmless springtails and can propel themselves by short flea-like jumps using their tail or furcula that is tucked under the body. In late winter these tiny dark grey-blue creatures (they are only 1-2 mm long) crawl about in masses on top of snow. They may be feeding, but the literature is uncertain on this matter. Normally they live in the soil feeding on detritus, algae, bacteria, and fungus. In terms of soil animals, their populations form some of the largest sources of biomass .