Blackhole Pro

Blackhole Pro is a WordPress security plugin that automatically detects and traps bad bots in a virtual blackhole, where they are blocked from your site. Blackhole Pro adds a hidden link to your pages. You add a rule to your robots.txt that instructs bots to stay away. Good bots will obey the rule, but bad bots will ignore it and follow the link right into the blackhole trap. Once trapped, bad bots are blocked and denied further access to your entire site.