To identify a caterpillar, begin by examining the body's color and any markings it has. Then note the density of the small hairs on the body, and look for some different physical properties, such as the head horn, spines or a curved tail. Once you have noted the physical characteristics of the caterpillar, enter them in an online identification guide to find images of a similar nature. Finally, look through the pictures to see which one suits you closest to the caterpillar you saw. To learn how to tell if something is a caterpillar, keep reading!