Here is a way to block all bad bots. Paste this code (and test after that) in your .htaccess file
# 2013 UA BLACKLIST [1/3]
<IfModule mod_rewrite.c>
RewriteCond %{HTTP_HOST} !^(127\.0\.0\.0|localhost) [NC]
RewriteCond %{HTTP_USER_AGENT} (\<|\>|\'|\$x0E|\%0A|\%0D|\%27|\%3C|\%3E|\%00|\@\$x|\!susie|\_irc|\_works|\+select\+|\+union\+|\<\?|1\,\1\,1\,|3gse|4all|4anything|5\.1\;\ xv6875\)|59\.64\.153\.|85\.17\.|88\.0\.106\.|98|a\_browser|a1\ site|abac|abach|abby|aberja|abilon|abont|abot|accept|access|accoo|accoon|aceftp|acme|active|address|adopt|adress|advisor|agent|ahead|aihit|aipbot|alarm|albert|alek|alexa\ toolbar\;\ \(r1\ 1\.5\)|alltop|alma|alot|alpha|america\ online\ browser\ 1\.1|amfi|amfibi|anal|andit|anon|ansearch|answer|answerbus|answerchase|antivirx|apollo|appie|arach|archive|arian|aboutoil|asps|aster|atari|atlocal|atom|atrax|atrop|attrib|autoh|autohot|av\ fetch|avsearch|axod|axon|baboom|baby|back|baid|bali|bandit|barry|basichttp|batch|bdfetch|beat|beaut|become|bee|beij|betabot|biglotron|bilgi|binlar|bison|bitacle|bitly|blaiz|blitz|blogl|blogscope|blogzice|bloob|blow|bord|bond|boris|bost|bot\.ara|botje|botw|bpimage|brand|brok|broth|browseabit|browsex|bruin|bsalsa|bsdseek|built|bulls|bumble|bunny|busca|busi|buy|bwh3|cafek|cafi|camel|cand|captu|casper|catch|ccbot|ccubee|cd34|ceg|cfnetwork|cgichk|cha0s|chang|chaos|char|char\(|chase\ x|check\_http|checker|checkonly|checkprivacy|chek|chill|chttpclient|cipinet|cisco|cita|citeseer|clam|claria|claw|cloak|clshttp|clush|coast|cmsworldmap|code\.com|cogent|coldfusion|coll|collect|comb|combine|commentreader|common|comodo|compan|compatible\-|conc|conduc|contact|control|contype|conv|cool|copi|copy|coral|corn|cosmos|costa|cowbot|cr4nk|craft|cralwer|crank|crap|crawler0|crazy|cres|cs\-cz|cshttp|cuill|CURI|curl|curry|custo|cute|cyber|cz3|czx|daily|dalvik|daobot|dark|darwin|data|daten|dcbot|dcs|dds\ explorer|deep|deps|detect|dex|diam|diavol|diibot|dillo|ding|disc|disp|ditto|dlc|doco|dotbot|drag|drec|dsdl|dsok|dts|duck|dumb|eag|earn|earthcom|easydl|ebin|echo|edco|egoto|elnsb5|email|emer|empas|encyclo|enfi|enhan|enterprise\_search|envolk|erck|erocr|eventax|evere|evil|ewh|exac|exploit|expre|extra|eyen|fang|fast|fastbug|faxo|fdse|feed24|feeddisc|feedfinder|feedhub|fetch|filan|fileboo|fimap|find|firebat|firedownload\/1\.2pre\ firefox\/3\.6|firefox\/0|firs|flam|flash|flexum|flicky|flip|fly|focus|fooky|forum|forv|fost|foto|foun|fount|foxy\/1\;|free|friend|frontpage|fuck|fuer|futile|fyber|gais|galbot|gbpl|gecko\/2001|gecko\/2002|gecko\/2006|gecko\/2009042316|gener|geni|geo|geona|geth|getr|getw|ggl|gira|gluc|gnome|go\!zilla|goforit|goldfire|gonzo|google\ wireless|gosearch|got\-it|gozilla|grab|graf|greg|grub|grup|gsa\-cra|gsearch|gt\:\:www|guidebot|guruji|gyps|haha|hailo|harv|hash|hatena|hax|head|helm|herit|heritrix|hgre|hippo|hloader|hmse|hmview|holm|holy|hotbar\ 4\.4\.5\.0|hpprint|href\s|httpclient|httpconnect|httplib|httrack|human|huron|hverify|hybrid|hyper|ia_archiver|iaskspi|ibm\ evv|iccra|ichiro|icopy|ics\)|ida|ie\/5\.0|ieauto|iempt|iexplore\.exe|ilium|ilse|iltrov|indexer|indy|ineturl|infonav|innerpr|inspect|insuran|intellig|interget|internet\_explorer|internet\x|intraf|ip2|ipsel|irlbot|isc\_sys|isilo|isrccrawler|isspi|jady|jaka|jam|jenn|jet|jiro|jobo|joc|jupit|just|jyx|jyxo|kash|kazo|kbee|kenjin|kernel|keywo|kfsw|kkma|kmc|know|kosmix|krae|krug|ksibot|ktxn|kum|labs|lanshan|lapo|larbin|leech|lets|lexi|lexxe|libby|libcrawl|libcurl|libfetch|libweb|light|linc|lingue|linkcheck|linklint|linkman|lint|list|litefeeds|livedoor|livejournal|liveup|lmq|loader|locu|london|lone|loop|lork|lth\_|lwp|mac\_f|magi|magp|mail\.ru|main|majest|mam|mama|mana|marketwire|masc|mass|mata|mvi|mcbot|mecha|mechanize|mediapartners|metadata|metalogger|metaspin|metauri|mete|mib\/2\.2|microsoft\.url|microsoft\_internet\_explorer|mido|miggi|miix|mindjet|mindman|miner|mips|mira|mire|miss|mist|mizz|mj12|mlbot|mlm|mnog|moge|moje|mooz|more|mouse|mozdex) [NC]
RewriteRule .* - [G]
</IfModule>
# 2013 UA BLACKLIST [1/3]
<IfModule mod_rewrite.c>
RewriteCond %{HTTP_HOST} !^(127\.0\.0\.0|localhost) [NC]
RewriteCond %{HTTP_USER_AGENT} (\<|\>|\'|\$x0E|\%0A|\%0D|\%27|\%3C|\%3E|\%00|\@\$x|\!susie|\_irc|\_works|\+select\+|\+union\+|\<\?|1\,\1\,1\,|3gse|4all|4anything|5\.1\;\ xv6875\)|59\.64\.153\.|85\.17\.|88\.0\.106\.|98|a\_browser|a1\ site|abac|abach|abby|aberja|abilon|abont|abot|accept|access|accoo|accoon|aceftp|acme|active|address|adopt|adress|advisor|agent|ahead|aihit|aipbot|alarm|albert|alek|alexa\ toolbar\;\ \(r1\ 1\.5\)|alltop|alma|alot|alpha|america\ online\ browser\ 1\.1|amfi|amfibi|anal|andit|anon|ansearch|answer|answerbus|answerchase|antivirx|apollo|appie|arach|archive|arian|aboutoil|asps|aster|atari|atlocal|atom|atrax|atrop|attrib|autoh|autohot|av\ fetch|avsearch|axod|axon|baboom|baby|back|baid|bali|bandit|barry|basichttp|batch|bdfetch|beat|beaut|become|bee|beij|betabot|biglotron|bilgi|binlar|bison|bitacle|bitly|blaiz|blitz|blogl|blogscope|blogzice|bloob|blow|bord|bond|boris|bost|bot\.ara|botje|botw|bpimage|brand|brok|broth|browseabit|browsex|bruin|bsalsa|bsdseek|built|bulls|bumble|bunny|busca|busi|buy|bwh3|cafek|cafi|camel|cand|captu|casper|catch|ccbot|ccubee|cd34|ceg|cfnetwork|cgichk|cha0s|chang|chaos|char|char\(|chase\ x|check\_http|checker|checkonly|checkprivacy|chek|chill|chttpclient|cipinet|cisco|cita|citeseer|clam|claria|claw|cloak|clshttp|clush|coast|cmsworldmap|code\.com|cogent|coldfusion|coll|collect|comb|combine|commentreader|common|comodo|compan|compatible\-|conc|conduc|contact|control|contype|conv|cool|copi|copy|coral|corn|cosmos|costa|cowbot|cr4nk|craft|cralwer|crank|crap|crawler0|crazy|cres|cs\-cz|cshttp|cuill|CURI|curl|curry|custo|cute|cyber|cz3|czx|daily|dalvik|daobot|dark|darwin|data|daten|dcbot|dcs|dds\ explorer|deep|deps|detect|dex|diam|diavol|diibot|dillo|ding|disc|disp|ditto|dlc|doco|dotbot|drag|drec|dsdl|dsok|dts|duck|dumb|eag|earn|earthcom|easydl|ebin|echo|edco|egoto|elnsb5|email|emer|empas|encyclo|enfi|enhan|enterprise\_search|envolk|erck|erocr|eventax|evere|evil|ewh|exac|exploit|expre|extra|eyen|fang|fast|fastbug|faxo|fdse|feed24|feeddisc|feedfinder|feedhub|fetch|filan|fileboo|fimap|find|firebat|firedownload\/1\.2pre\ firefox\/3\.6|firefox\/0|firs|flam|flash|flexum|flicky|flip|fly|focus|fooky|forum|forv|fost|foto|foun|fount|foxy\/1\;|free|friend|frontpage|fuck|fuer|futile|fyber|gais|galbot|gbpl|gecko\/2001|gecko\/2002|gecko\/2006|gecko\/2009042316|gener|geni|geo|geona|geth|getr|getw|ggl|gira|gluc|gnome|go\!zilla|goforit|goldfire|gonzo|google\ wireless|gosearch|got\-it|gozilla|grab|graf|greg|grub|grup|gsa\-cra|gsearch|gt\:\:www|guidebot|guruji|gyps|haha|hailo|harv|hash|hatena|hax|head|helm|herit|heritrix|hgre|hippo|hloader|hmse|hmview|holm|holy|hotbar\ 4\.4\.5\.0|hpprint|href\s|httpclient|httpconnect|httplib|httrack|human|huron|hverify|hybrid|hyper|ia_archiver|iaskspi|ibm\ evv|iccra|ichiro|icopy|ics\)|ida|ie\/5\.0|ieauto|iempt|iexplore\.exe|ilium|ilse|iltrov|indexer|indy|ineturl|infonav|innerpr|inspect|insuran|intellig|interget|internet\_explorer|internet\x|intraf|ip2|ipsel|irlbot|isc\_sys|isilo|isrccrawler|isspi|jady|jaka|jam|jenn|jet|jiro|jobo|joc|jupit|just|jyx|jyxo|kash|kazo|kbee|kenjin|kernel|keywo|kfsw|kkma|kmc|know|kosmix|krae|krug|ksibot|ktxn|kum|labs|lanshan|lapo|larbin|leech|lets|lexi|lexxe|libby|libcrawl|libcurl|libfetch|libweb|light|linc|lingue|linkcheck|linklint|linkman|lint|list|litefeeds|livedoor|livejournal|liveup|lmq|loader|locu|london|lone|loop|lork|lth\_|lwp|mac\_f|magi|magp|mail\.ru|main|majest|mam|mama|mana|marketwire|masc|mass|mata|mvi|mcbot|mecha|mechanize|mediapartners|metadata|metalogger|metaspin|metauri|mete|mib\/2\.2|microsoft\.url|microsoft\_internet\_explorer|mido|miggi|miix|mindjet|mindman|miner|mips|mira|mire|miss|mist|mizz|mj12|mlbot|mlm|mnog|moge|moje|mooz|more|mouse|mozdex) [NC]
RewriteRule .* - [G]
</IfModule>
