Cave spiders not posioning

Put the summary of the bug you're having here

What I expected to happen was...:
Getting hit by cave spiders would cause me to get poisoned

What actually happened was...:
Cleared out 4 generators in the mines and never once got poisoned.

Additional Info:
Server machine (Win 8.1) running 1.6.1
2 clients connected (Win 8.1 and Vista) running 1.6.1
Survival Mode
Difficulty: Normal
Last time encountered: Friday June 28th

I have searched and noted several other tickets put in but all I found showed resolved so I added this.