Do I have spambots reading my LJ?

I think that some of the latest users to friend my LJ are spambots: specifically abarot, albatius, axtty, and balaklavaris. Why? (1) They don’t post anything, which would make sense if they are bots, because their posts would eventually give them away. (2) No known humans appear to be friending them back, they are only friends with one another. (3) Their profiles are empty, except for one which has a link to what appears to be the homepage of two gay lovers, but which I suspect is a site designed to raise the Google rank of some related gay porn sites.

What should I do? I can’t prove that they’re spammers, but if they are they should be kicked before they can waste everyone’s time.