The Corn Snake or Red Rat Snake, is a North American species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of Rat Snake

Rat snake

Rat snakes are medium to large constrictors that can be found through a great portion of the northern hemisphere. They feed primarily on rodents and birds and, with some species exceeding 3 m , they can occupy top levels of some food chains. Many species make attractive and docile pets and one,...

 that subdues its small prey by constriction. The name "Corn Snake" is a holdover from the days when southern farmers stored harvested ears of corn in a wood frame or log building called a crib. Rats and mice came to the corn crib to feed on the corn, and Corn Snakes came to feed on the rodents. The Oxford English Dictionary

Oxford English Dictionary

The Oxford English Dictionary , published by the Oxford University Press, is the self-styled premier dictionary of the English language. Two fully bound print editions of the OED have been published under its current name, in 1928 and 1989. The first edition was published in twelve volumes , and...

 cites this usage as far back as 1676.