Crystal Spider

The best counter to Anomalus IMO (H/S). Start with Brittle Webbing, then depends of Anomalus'es move - if Void Slap/Toxic Fumes then Leech Life/Spiderling Swarm, then (or otherwise, depends on enemy's move) Crystal Prison and watch Anomalus melt down with its own weapon ;). Very underrated and very, VERY good pet ;).

I spent about an hour flying from the lake to the gorge and only three spawned, all of them poor quality. Hit up two random critter in the zone and there was a Rare Crystal Spider on the second. Might just be worth looking around at random pets instead of farming the specific spawn points.

The Only spider with a stun~! Making it good for delaying certain actions like Wish with Zao.

These are found only in Winterspring, at the frozen lake and the gorge (ignore the out of date comments below). Pain in the buns to farm for a rare. Their spawns appear to be tied to the other nearby critters, so if you don't find any, go massacre the bunnies and squirrels. I was able to spawn 1-3 at a time using this method. Have been farming for a few hours with no luck, hopefully your hunt is easier =/

found the area roday. after a surch.

and after a hour or so found a rare. in winter. :D 

couldnt be happier. 

found him in frostwisper. in the vally.

Winter is not the best season to look for your rare Crystal Spider, because many Snowy Owls spawns in their places.

I must have the worst luck ever, spent the last 2 hrs spinning in circles to get a rare and still no luck.

This pet is on both the Eastern Kingdoms and Kalimdor Safari achievement. Reports tho say that it is only captureable in Winterspring.

Check around the lake or down in frostwhisper grove in winterspring

Caught one on the upper rim of Frostwhisper Gorge as a 3rd position.  Little bugger was a bit tricky to catch as he kept healing just a bit before I could throw the trap or after just missing.  Be versatile with this one.  It wasn't hard but I didn't want to squash it.  Now to find a rare  :P

Found right at Frostwind Gorge, all the way south in Winterspring.

Found mine as an add on an alpine chipmunk in the north end of Winterspring.

I was just able to find one twice in battles with an alpine chipmunk in Winterspring.  If it doesn't join the battle as one of the other pets, then you can forfeit and start another battle until it appears.  If it matters, the chipmunks I fought were southeast of Everlook.

After a thorough search in Dun Morogh (including a short, but extremely painful anti-air attack from some gnomes), I couldn't find any trace of these there. I'm guessing it's outdated data from an old quest I seem to remember, in the Dwarf starting zone where there was a cave with them.

I can't find any in Dun Morogh. I checked the map on Wowhead and, while I didn't take time to click every single beast icon, every one I did click was a snow cub. Are they just that hard to find?