My current top-level .htaccess:
SetEnvIfNoCase User-Agent ".*noxtrumbot*." spambot=1
SetEnvIfNoCase User-Agent ".*Indy Library.*" spambot=1
SetEnvIfNoCase User-Agent ".*Zeus.*" spambot=1
SetEnvIfNoCase User-Agent ".*linko*." spambot=1
SetEnvIfNoCase User-Agent ".*imagefetch*." spambot=1
SetEnvIfNoCase User-Agent ".*urniti*." spambot=1
SetEnvIfNoCase User-Agent ".*kuloko-bot*." spambot=1
SetEnvIfNoCase User-Agent ".*nameprotect*." spambot=1
SetEnvIfNoCase User-Agent ".*grub-client*." spambot=1
SetEnvIfNoCase User-Agent ".*WebCopier*." spambot=1
SetEnvIfNoCase User-Agent ".*Zyborg*." spambot=1
SetEnvIfNoCase User-Agent ".*WebZIP*." spambot=1
SetEnvIfNoCase User-Agent ".*Downloader*." spambot=1
SetEnvIfNoCase User-Agent ".*Ninja*." spambot=1
SetEnvIfNoCase User-Agent ".*OmniExplorer_Bot*." spambot=1
SetEnvIfNoCase User-Agent ".*omni-explorer*." spambot=1
SetEnvIfNoCase User-Agent ".*NG/2.0*." spambot=1
SetEnvIfNoCase User-Agent ".*WebStripper*." spambot=1
SetEnvIfNoCase User-Agent ".*mafin*." spambot=1
SetEnvIfNoCase User-Agent ".*MAFin*." spambot=1
SetEnvIfNoCase User-Agent ".*Snapbot*." spambot=1
SetEnvIfNoCase User-Agent ".*QihooBot*." spambot=1
SetEnvIfNoCase User-Agent ".*Baiduspider*." spambot=1
SetEnvIfNoCase User-Agent ".*baiduspider*." spambot=1
SetEnvIfNoCase User-Agent ".*iaskspider*." spambot=1
SetEnvIfNoCase User-Agent ".*Scanner*." spambot=1
SetEnvIfNoCase User-Agent ".*IRLbot*." spambot=1
SetEnvIfNoCase User-Agent ".*HTTrack*." spambot=1
SetEnvIfNoCase User-Agent ".*MSNPTC*." spambot=1
SetEnvIfNoCase Referer
www.addresses.com spambot=1
SetEnvIfNoCase Referer
www.bwdow.com spambot=1
<Limit GET POST PUT>
Order allow,deny
Deny from 207.210.101.49
Deny from 210.82.118.14
Deny from 208.77.96.98
Deny from 82.99.30
Deny from 207.210.101.4
Deny from 64.79.219.5
Deny from 193.1.100.110
Deny from 86.95.251.198
Deny from 87.210.41.139
Deny from 164.100.111.69
Deny from 81.168.228.218
Deny from 200.73.70.195
Deny from 66.16.63.44
Deny from 88.45.219.250
Deny from 194.7.161.130
Deny from 65.112.42.83
Deny from 209.191.123.34
Deny from 212.241.248.10
Deny from 88.151.114.33
Deny from 65.88.178.10
Deny from 66.195.77.130
Deny from 194.27.13.195
Deny from 141.11.234.60
Deny from 65.19.150
Deny from 6.234.139
Deny from 38.99.203.110
Deny from 204.9.204.202
Deny from 60.28.17.43
Deny from 210.173.180.145
Deny from 64.27.31.205
Deny from 137.82.84.97
Deny from 88.151.114.37
Deny from env=spambot
Allow from all
</Limit>