An unusually large amount of guests vs users

[PBRiot]

My forum is www.pbriot.com/forum.php. It's a small forum, I haven't really launched yet - I have 8 users online and 61 guests, which I know is inaccurate. I know that many/some of those guests are bots, but that seems like a LOT of guests/bots, and it appears that the number of guests keeps rising every day, as if the cache isn't getting cleared.

Ideas or suggestions on how to reduce the load/incorrect numbers, etc?