This snake can grow to 1,520 mm but in Arizona most individuals are less than 890 mm or 35" in total length. The head is narrow, the lower jaw is countersunk, and, in profile, the snout is pointed.
The scales are smooth and shiny, most of the subcaudal scales are undivided, the pupils are round, and the irises are red or orange. Body markings are highly variable but generally consist of black saddles surrounded by white, cream, or yellow interspaces with or without pinkish red suffusions. Most Arizona specimens fit into one of two pattern morphs: "clarus morph" or "lecontei morph".
LECONTEI morph snakes possess 19-48 black saddles with light interspaces. The black saddles are usually solid dorsally and taper to a jagged-edged, light-speckled, triangle shape laterally. On the lateral surfaces of the body the black saddles contain light speckles and the light interspaces contain dark speckles. Pink or red coloration is often present in the interspaces in the form of speckles, patches, or suffusions. In lecontei specimens the underside is either plain or marked with small triangular or square flecks on the ventrolateral seam. Its red or orange irises and undivided subcaudals distinguish this snake from the Thornscrub Hook-nosed Snake.
CLARUS morph snakes possess 12-27 broad, relatively smooth-edged saddles with light interspaces. Saddles are usually solid black dorsally and contain a central patch of light centered scales laterally. Clarus specimens often lack red coloration but some Arizona claris specimens have a glaze of pinkish-red over the light interspaces. In clarus specimens the underside is usually marked with small to medium-sized black squares or bars and some have large black or dark gray ventral patches. Its red or orange irises and undivided subcaudals distinguish this snake from the Common Kingsnake.
This common and widespread snake is found across the flatlands and valleys of southern and western Arizona at elevations ranging from near sea level along the Colorado River to about 6,000'. It is also found on the plateaus of the Arizona Strip (land north of the Colorado River).
In Arizona it is found primarily in sparsely vegetated desertscrub communities and Semidesert Grassland but it extends up into the lower reaches of the woodlands in some areas. It inhabits low desert ranges, foothills, valleys, and flatlands with sandy, gravelly, or moderately rocky soils. It is usually absent from steep mountainous terrain.
This ground-dweller is almost exclusively nocturnal in Arizona. In Arizona it is normally active from April through September and it hibernates underground during the cold months of late fall and winter. It uses its enlarged and pointed rostral scale to burrow undergroung for shelter and to unearth shallowly-buried lizard prey. When captured or threatened it may writhe and hide its head beneath its coils, vibrate its tail, evert the lining of the cloaca, and releasing musk and foul-smelling waste. Females have been observed to release blood from the cloaca, nostrils, and mouth during defensive displays. Rhinocheilus lecontei rarely bites when captured.
The Long-nosed Snake is a constrictor that actively forages for lizards, small mammals, snake and lizard eggs, and occasionally grasshoppers. Whiptail lizards (Aspidoscelis) make up a large percentage of its diet. Small snakes feed almost exclusively on lizards. Larger individuals include small mammals in their diet.
Mating probably takes place primarily in April and May. Studies suggest that not all females breed each year. Egg laying takes place mainly in June and July, but August oviposition has been reported as well. Clutch size ranges from 3 to 11 eggs. Incubation periods range from 42 to 90 days and most eggs hatch in August or September.