Re: why do cats like to chew on grape stems?

I consider myself well educated on cat behavior (although I am no expert). 
 I have never heard any reference to grape stems having an affect, like 
catnip does, on cats.  Therefore, I would say it is most likely the way the 
stems bounce around that makes them fun for cats to play with.

Thanks for the question and have fun with your cat!!

Janet Hoff
Licensed Veterinary Technicain