Snow fleas (springtails) are not insects

Not any more.  They've been reclassified - as explained by Karen Oberhauser, Director of the University of Wisconsin-Madison Arboretum:

If you’re thinking that the snow fleas you might see count as insects, think again! As I’ve recently learned, snow fleas are no longer considered insects. Their old insect order, Collembola, was moved into a new class called Entognatha. Collembola, more commonly known as springtails, comprise the largest order in this class.

Why aren’t they insects? Like insects, they have bodies with three parts, and six legs. But unlike insects, they have soft bodies, no wings, and simple eyes. Their eyes, for example, are more like the eyes on crustaceans or on immature insects like caterpillars. Their mouthparts are tucked into their heads, not out in the open like insects’ mouthparts. The source of their common name, “springtail,” is an appendage that many Collembola have, a “furca,” which is held under their abdomen and allows them to jump – or spring – away from danger. Given the abundance of springtails, the furcas appear to be quite effective.

For an outstanding source on soil microfauna, visit A Chaos of Delight - whence the photo (cropped for size), with many more in the gallery.