IP banning can be dangerous. I remember on my old site we were looking through IPs and noticed a few members had the same address. Turns out that they had a shared community with a suburb like wifi zone.

So you can set up something that could where you took the address and banned them, but you don'tknow how many others may be affected.

A better option might be an email blacklist seeing as your bots tend to use custom sites and/or temporary emails. However again, blacklisting is dangerous.