During a feeding response two captive N.n. helvetics grabbed and each chewed one finger of the author for a while. In that process the snakes used their fangs which caused local pain for the bite victim. A mild swelling and discoloration at the bite site followed it lasted for two days. The author stressed the fact that this species in general bites seldomly and that ***normal*** quick bites during feeding response never caused any signs of envenomation. This is in line with reports of other authors (like Mebs, D. (2000): Gifttiere. - Stuttgart (Wiss.
Verl.-Ges.) who described venom apparatus as inefficient. Snake has to chew for a longer time to enable envenomation.