A medium (up to 1,120 mm or 44" in total length) reddish-brown to olive-brown snake with a single cream colored stripe down the middle of the back (dorsal stripe).
The dorsal stripe is crisp-edged and is sometimes bordered by a thin dark line along each side. An additional thin light stripe lines each lower side on the 3rd and 4th scale rows (counting up from the belly). Alternating blotches composed of short, dark, tightly stacked dashes mark the areas between the light stripes. These dark blotches do not intrude into the dorsal stripe. The underside is pale. Dark bars mark the seams of the upper lip scales (upper labials). The pupils are round and the dorsal scales are keeled.
This snake is now absent from much of its historic range in Arizona. It was once found in many of the sub-Mogollon Rim drainage systems across the central portion of Arizona and several drainage systems in south-central and southeastern Arizona. It remains in only a few isolated populations below the rim and in south central Arizona. Elevation ranges from about 1,000' to about 6,700'.
It is usually found in or near rivers, streams, and ciénegas in communities ranging from Arizona Upland Sonoran Desertscrub, through Semidesert Grassland and the woodlands, into Petran Montane Conifer Forest.
This primarily diurnal snake often forages in the mid-morning sun. It hibernates during the cold months of late fall and winter. When encountered it is quick to dive under the water. When persistently harassed it has been observed to tuck the head down against the ground and under the coils, hold the head and fore-body motionless, and "crawl" the wiggling tail away from the body (author obs.). This behavior may be serve to divert a predators attention away from the head and to the tail.
The Mexican Gartersnake eats frogs, toads, fish, lizards, and small mammals.
Mating takes place in spring and young are born in June and July.
Protected in Arizona. It is against Arizona State law to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect this animal or to attempt to engage in any such conduct.