Key to Snakes of Washington

1. 1. Deep pit between nostril and eye; rattle on tail tip .....Western Rattlesnake, Crotalus viridis
   2. No deep pit or rattle .....2
2. 1. No enlarged chin shields; blunt tail .....Rubber Boa, Charina bottae
   2. Two pairs of enlarged chin shields; tail long and pointed (unless broken off) .....3
3. 1. Some or all dorsal scales keeled .....4
   2. All dorsal scales smooth .....7
4. 1. Four prefrontals; body with large blotches .....Gopher Snake, Pituophis catenifer
   2. Two prefrontals; body striped or with small spots .....5
5. 1. Eight upper labials; conspicuous checkered pattern .....Western Terrestrial Garter Snake, Thamnophis elegans
   2. Seven upper labials; never with conspicuous checkered pattern, although sometimes with dots .....6
6. 1. 17 scale rows at midbody; usually a dark postocular stripe contrasting with paler head color; pattern very variable (dorsal stripe may be lacking, ground color may be pale) .....Northwestern Garter Snake, Thamnophis ordinoides
   2. 19 scale rows at midbody; head usually all dark above; always dark with light stripes above .....Common Garter Snake, Thamnophis sirtalis
7. 1. Anal plate entire; body brightly banded .....California Mountain Kingsnake, Lampropeltis zonata
   2. Anal plate divided; not brightly banded .....8
8. 1. Spine on tip of tail; belly finely barred with black .....Sharptail Snake, Contia tenuis
   2. No spine on tail tip; belly colored otherwise .....9
9. 1. Orange belly and ring around neck .....Ringneck Snake, Diadophis punctatus
   2. No neck ring; belly colored otherwise .....10
10. 1. Pupil vertical; spotted above, with large blotches on neck .....Night Snake, Hypsiglena torquata
    2. Pupil round; unicolor, striped or spotted, no large blotches on neck .....11
11. 1. Finely striped above Striped Whipsnake, Masticophis taeniatus
    2. Unicolor (adults) or finely spotted or banded above (young) .....Racer, Coluber constrictor

Adapted by Dennis Paulson from key in Nussbaum, R. A., E. D. Brodie, Jr., and R. M. Storm. 1983. Amphibians & Reptiles of the Pacific Northwest. Univ. Press of Idaho, Moscow.