Are all pit vipers poisonous?

Pit vipers (Crotalinae) are so named because of their characteristic loreal pits, organs on each side of their head between nostril and eye, which act as heat-detectors.

They are venomous and should, like all snakes, be treated with respect and commonsense.

Always assume any snake to be potentially venomous; leave it alone. Most snakebite victims are bitten when attempting to catch, kill, or in some way handle the snake.

It is dangerous to decide a snake is non-venomous, or to act upon information which suggests a venomous snake is 'not very' poisonous, and therefore to treat it casually.

Even experienced handlers, scientists, and other experts can get it wrong when it comes to identification, but those expert in dealing with snakes certainly know enough to be certain that one can never be entirely certain!

There is no need to become paranoid about snakes; the incident of human snakebite victims is comparatively low; snakes will go quickly in the opposite direction when sensing the approach of something as large and heavy as a human.