Snakes inhabit every part of the United States, and learning to identify the ones you see around your home first involves learning to identify the venomous snakes around your area. To identify snakes, you'll need to look at their characteristics and size. Most of the venomous snakes in the United States belong to the family Viperidae, the pit vipers, named after the heat-sensing pit in between their eye and nostril. While snakes may seem to be a pest or might even scare you, snakes are among the most beneficial predators in your yard against pests such as rodents, amphibians and other creatures.
Watch the snake closely and take a picture if you have a camera handy or even a cell phone that takes decent photographs. If you don't, but there are other people around, ask if someone can grab a camera and get a photograph. While this isn't necessary, a photograph can help you identify the snake. Don't leave the snake to get a camera, they are very quick and chances are that the snake will be long gone before you return with a camera.
Look at the snake's markings. You'll need to determine if it's patterned, plain, two-toned or striped. "Patterned" refers to the snake having an irregular pattern or one that does not consist of just stripes. Patterned snakes generally have blotches or spots. Plain snakes are almost completely uniform in color with no distinguishing stripes, splotches or other markings. Two-toned snakes are predominately two colors, typically one color on top and another on the belly. Striped snakes may have any number of stripes that run parallel with the body. This is normally the best way to identify a snake.
Determine, to the best of your ability, how large the snake is. While this sometimes only works for mature snakes, it can greatly help you identify the snake. Garter snakes, the most common snake throughout their ranges, typically range from 1 1/2 feet to more than 4 feet long. The various racers grow from almost 3 feet to more than 6 feet long. The rat snakes can grow to more than 8 feet long. Small snakes include those that may not even grow to 8 inches, such as many of the crowned snakes.
Look at the snake's eyes if you are close enough. Pit vipers have vertical pupils, much like a cat's eyes. Other snakes have round pupils. Also, pit vipers often give a visual or audible warning sign before striking; rattlesnakes shake their rattling tails while cottonmouths open their gaping mouths to show the cottony-white inside.
Look up the snake in a snake, reptiles and amphibians or similar field guide. You can borrow these from the library. A good field guide has detailed pictures and descriptions. Some field guides even separate the snakes by markings to help you find the snake quicker.
Conduct an educational website search online for snakes. For example, if you found a large black snake and you live in Indiana, you could type in "site:.edu large black snakes in Indiana." The "site:.edu limits the results to university and educational websites only. You can also add the word "pictures" to the end of the search to get helpful photographs.
Contact your local cooperative extension, department of natural resources or animal control if you still cannot identify the snake.