What are these guys?

[MSchep]

Just reaching out here for some ID help on these critters? They don't seem to be doing much damage that I can see (so far, anyway), and they appear to like the Early Girl leaves much more than any of the other cherry varieties I have. Thinking Aphids, but don't have enough pest experience to know for sure and I thought those were really only a problem when it gets hot (we have only cracked 80deg here for a couple days so far)?

Thanks in advance for your thoughts on what these are, and if I should be concerned?