Since this topic keeps reviving, here is the official USCCA stance on wasp spray for self-defense:
The USCCA cannot stress enough for you to never use wasp/hornet spray as a self-defense weapon. Wasp spray is an insecticide, and Federal Law prohibits the use of any pesticide or insecticide “in a manner that is inconsistent with its labeling.’’ You could face federal criminal charges. Wasp spray is very good at what it is designed for, which is killing wasps. The main ingredient of pepper spray is capsaicin, an oil extracted from chili peppers which temporarily causes severe irritation of the eyes and lungs, producing a strong burning sensation and difficulty breathing. Wasp sprays, on the other hand, consist of one or more insecticides such as pyrethrum or propoxur. While the toxic side-effects of such chemicals do, in fact, include eye and lung irritation in humans, they are chemical poisons, the main purpose of which is killing pests.
Wasp spray is not for self-defense.