As most of you will know there is a achievement in Cataclysm to get 50.000 critter kills with your guild.
Critter Kill Squad - Achievement - World of Warcraft
And even 100.000 kills
Crittergeddon - Achievement - World of Warcraft
I had been thinking about good spots to get this done and then I accidentally came across this area in Dragonblight. It's inside Agmar's Hammer. The coordinates are around 36.4 , 48.3
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This is what it looked like after a minute or so.
[spoiler][/spoiler]
The critters here respawn almost instantly after being killed. So you can get a lot of fast kills by AOE-ing the hell out of this area. I don't know if alliance players will agro guards if they come in here, but they can probably land on the wall and AOE from there without having too much guard issues. Hordies can go mental either way.
I figured this is not a intended way to farm critters so I posted it here rather than guides.
Now put on those bug stomping boots and get going!
Edit:
TIP:
Go into Interface -> Names!
Check Critters and Companions here to see the little buggers easier!
Macro to target closest critter:
/cleartarget
/tar [nodead] Cockroach