Q: I see several small block dots moving on my snake--what is that?
A: Welcome to the wonderful world of snake mites. They are the most common parasite that you will encounter and one of the biggest pains to get rid of. I have personally used Sevin Dust without a problem, but some people recommend a diluted Nix treatement. Since I have no experience with that, I will just link some threads regarding the issue.
I suggest that you search the forum for the topic of "mites" you should get plenty of result's.
Thanks and good luck.
Ryan