The fact that snakes never blink may also have played a role in this myth's origin. Barns are attractive to milk snakes because they provide abundant food in the form of small rats and mice. Although the bite of a hognose snake can produce swelling and a burning sensation, these snakes rarely bite people and are not considered poisonous. When confronted, they do puff themselves up and hiss, but their breath is harmless. The cottonmouth, or water moccasin, is a poisonous snake of the southeastern United States that occurs no farther north than the Great Dismal Swamp of Virginia.
Many people mistake nonpoisonous water snakes for water moccasins.