a harmless colubrid snake (Lampropeltis triangulum) with brown or reddish bands bordered by black: it feeds on rodents, reptiles, etc.
See milk snake in American Heritage Dictionary 4
noun
Any of various nonvenomous king snakes of the species Lampropeltis triangulum ranging from the eastern and central United States south to Ecuador, often having red, black, and yellow or white bands. Also called house snake, milk adder.