So I just had a look at your robots.txt:
User-Agent: *
Disallow: /login
Disallow: /login_reset
Disallow: /settings
Disallow: /create_community
Disallow: /create_post
Disallow: /create_private_message
Disallow: /inbox
Disallow: /setup
Disallow: /admin
Disallow: /password_change
Disallow: /search/
Disallow: /modlog
Crawl-delay: 60
You explicitly allow searching your content by bots... That's likely one of the reasons why you get bot traffic.