Although these little guys appear every Spring, that?s not how they get their common name. Instead, it comes from a little appendage under their abdomen called a Furcula. If they want to move a little, they use their legs. If they want to move a lot, out comes the Furcula. They might not know where it will send them, but it seems to get the job done.
When I came by several hours later, most of them had moved on. Somewhere....
I?m including a shot from my microscope. The hairs measure about 1/1000 " long.
The Furcula is the thing laid flat on his/her belly that it "springs" with.
They are also known as Snow Fleas.
Art