The latin name for those would be groundinus swininus namfoninus. Seriously, I don't know. But were they insects or maybe sow bugs? Mid thirties seems a little cool for cold blooded creatures, even without the snow. I'll do some searching around and see what I can come up with.. steve

Here is a link that might be useful: insect overwintering

Could be anything. Soil critters (worms, slugs, pillbugs etc.) are active at fairly low temps early and late in the season so its not a physiological problem for some of them. The sun could be warming up the paths moreso than the air temp and activated who knows what. Most bugs are hibernating a bit deep and do not thaw out as quickly as the snow melts.

There are two insects that I often see in the late winter. Springtail (sometimes called snow fleas....but they aren't really fleas) are usually smaller than your description and most "spring" along, unlike your scurrying description. Once I set my light colored pack down by a tree and when I turned to pick it up a few minutes later it was gray from all the springtails covering it. I've never seen so many springtails in one place ever again. And in case you care, many scientist no longer consider springtails insects for various reasons.

Stoneflies are often seen on top of the snow also. There are some species that are similar to your description, but the ones I see most often are larger and generally fly instead of scurry. The adults are usually near unpolluted streams where they spend the first part of their life as nymphs that live underwater. Trout feed on them and good fly fishermen know stoneflies well.

It always surprises me to see these critter out in the snow. Their dark bodies absorb some heat from the sun and help to warm them. They usually are out when temps are above freezing, but it seems like I sometimes see them moving even after temps drop. They amaze me with their resiliance

I don't know what the OP's insects could have been, but it was sunny and around 39 degrees here on Saturday. My bees were out taking cleansing flights, and I saw two other insect species myself -- some type of medium sized (like a large housefly) dark fly buzzing around on the siding on the south of my house, apparently sitting in the sun and warming up. I also saw some type of midge-like small insect flying around near a grove of small aspen trees. I thought it was a little cold, too, for these to be out, but there they were.

Denn,

Yes it probably was in the mid ~ upper 30s when we saw these critters.

Naturegirl,

I agree these were much longer than the description I found for Snow Fleas.

I may try and catch a couple and get them identified.

I would like to imagine that these guys have learned something that we haven't yet, like, when ( wee little guys come out it is safe to plant peas in 3 weeks or so LoL )

I've seen mosquitoes on snow, seemingly sipping at the melting ice.

Here are a few links to more info. Let us know if you recognize anything.
http://www.microscopy-uk.org.uk/mag/artjan99/basnow.html

http://www.newton.dep.anl.gov/natbltn/600-699/nb665.htm

http://my.whiotv.com/_OMG-Snow-Bugs-Really/photo/7918742/6688.html

http://www.gi.alaska.edu/ScienceForum/ASF15/1513.html

FWIW, I've found wasps moving on snow when the wind chill was minus 54. A good snow cover, bright sun, right time of the day. The snow reflected the light and heat up to the one spot where the nest was located. They made the mistake of thinking it was spring, thawed out and tried to leave the nest. Ah, was it sweet to see nine dead wasps on the white snow!

Mike

Just saw another possibility....snow scorpionfly....not outside but in Audubon magazine. Their online version has a small photo of the dark insect part way down the page on the far right. Scroll down to almost the bottom of the page to read the "Snow strutter" text in reasonable size print.

I'm going to start watching the snow better. Maybe I can spot a few of these interesting creatures someday.

Here is a link that might be useful: Audubon magazine.....snow scorpionfly