There are a few species of colubrids that are venomous. What is surprising to most people is that the common garter snake is mildly venomous. The venom doesn't really affect humans like their more venomous cousins, but if their bites do manage to break the skin enough to mix in their saliva, it contains venom that has a mildly neurotoxic effect. This can cause swelling, bruising, and numbness in the affected area. Such a bite is often described as a "bee sting".