Anurida sp.

I think you have photographed springtails. These are tiny insects, come in a number of different colors, are usually shaped like these, have short stubby antenna, etc. Take a look at this Bugguide.net page and see what you think: http://bugguide.net/node/view/97813. I see them up here in Minnesota at this time of year as the snow is melting back. They are often found on the snow around holes melted around trees and can occur in the thousands.