The eastern foxsnake, rare in Missouri, is a moderately large snake with distinct brown blotches. The ground color is gray, yellowish, greenish brown, or tan, with an average of 43 dark blotches on the back and sides with a brown to reddish-brown head. The belly is yellowish, marked with a prominent dark checkered pattern. When threatened, a foxsnake will vibrate its tail, coil with head and neck raised, and strike repeatedly to defend itself. When captured, foxsnakes give off a musky odor like the scent of a red fox, accounting for their name.
Young lack the yellow ground color and are gray with bold dark brown or black blotches. The head is boldly marked with a black mask running through the eyes and slanding back to the angle of the jaw. There are also black markings on top of the head and large black spots along the upper lips.
Hatchlings resemble western ratsnakes (black rat snakes). Counting ventral scales (belly scales, from neck to anus) is the best way to distinguish them (about 216 on foxsnakes, and about 221 on young western ratsnakes).
Similar species: The western foxsnake (P. ramspotti) is extremely similar to the eastern foxsnake. In Missouri, it is mainly identified by its different geographic distribution: the western foxsnake is restricted to a few counties in the northwestern corner of the state, while the eastern foxsnake occurs only in a few counties along the Mississippi River floodplain north from St. Louis. The western species has an average of 37 large brown blotches on the back and smaller ones on the sides.