I blocked Twiceler when the Bots section first appeared in UBBt.

Here's a current list of blocked bots in my .htaccess file that have visited and leached:
Code
RewriteEngine On
RewriteCond %{HTTP_REFERER} iaea\.org [OR]
RewriteCond %{HTTP_USER_AGENT} Baiduspider [OR]
RewriteCond %{HTTP_USER_AGENT} BecomeBot [OR]
RewriteCond %{HTTP_USER_AGENT} BecomeJPBot [OR]
RewriteCond %{HTTP_USER_AGENT} BilgiBot [OR]
RewriteCond %{HTTP_USER_AGENT} Bot [OR]
RewriteCond %{HTTP_USER_AGENT} ContactBot [OR]
RewriteCond %{HTTP_USER_AGENT} EmailSiphon [OR]
RewriteCond %{HTTP_USER_AGENT} Gaisbot [OR]
RewriteCond %{HTTP_USER_AGENT} ichiro [OR]
RewriteCond %{HTTP_USER_AGENT} "Indy Library" [OR]
RewriteCond %{HTTP_USER_AGENT} IRLbot [OR]
RewriteCond %{HTTP_USER_AGENT} libwww-perl [OR]
RewriteCond %{HTTP_USER_AGENT} LinkWalker [OR]
RewriteCond %{HTTP_USER_AGENT} MJ12bot [OR]
RewriteCond %{HTTP_USER_AGENT} my-heritrix-crawler [OR]
RewriteCond %{HTTP_USER_AGENT} Psbot [OR]
RewriteCond %{HTTP_USER_AGENT} PlantyNet_WebRobot [OR]
RewriteCond %{HTTP_USER_AGENT} RobSoft [OR]
RewriteCond %{HTTP_USER_AGENT} SBIder [OR]
RewriteCond %{HTTP_USER_AGENT} shelob [OR]
RewriteCond %{HTTP_USER_AGENT} sohu-search [OR]
RewriteCond %{HTTP_USER_AGENT} sogou [OR]
RewriteCond %{HTTP_USER_AGENT} sogou-spider [OR]
RewriteCond %{HTTP_USER_AGENT} sogou-web-spider [OR]
RewriteCond %{HTTP_USER_AGENT} Twiceler [OR]
RewriteCond %{HTTP_USER_AGENT} wwwster [OR]
RewriteCond %{HTTP_USER_AGENT} Y!J-SRD [OR]
RewriteCond %{HTTP_USER_AGENT} "Yahoo! Slurp China" [OR]
RewriteCond %{HTTP_USER_AGENT} YANDEX
RewriteRule .* - [F,L]