A chain email is circulating the ‘Net from someone claiming she was advised by her local police that wasp spray was a better alternative than pepper spray for personal safety. See http://www.snopes.com/crime/prevent/waspspray.asp
I often recommend any kind of caustic substance (like hair spray, perfume, deodorant or wasp spray) if you need to find a “weapon of opportunity” in your environment to fend off an attack.
I DON’T recommend any of these substances instead of pepper spray. Pepper spray is an extremely effective personal safety weapon. I did a great radio show on the topic of pepper spray – check it out!