Smooth greensnakes have been declared extirpated from Missouri, but perhaps someone may rediscover this gentle snake in grasslands in northern Missouri. Unlike the more common northern rough greensnake, the smooth greensnake lives in grasslands (not wooded areas) and would only be expected to occur in northern Missouri (not the Ozarks).
The smooth greensnake is a small, gentle, secretive species. The upperside color is bright green without any markings. The belly is plain white or with some yellow color along the sides. Individuals in the upper Midwest may be a uniform light tan instead of green, but this color form has not been reported in Missouri. The upperside scales are smooth (not keeled and rough-feeling).
Upon death, greensnakes turn pale blue.
When captured, a specimen may struggle to escape but seldom attempts to bite.
Similar species: The northern rough greensnake (O. aestivus aestivus) is more common in Missouri. Its upperside scales are ridged, so it feels rough to the touch (not smooth). It is slightly larger and has a proportionately longer tail. Also, it generally lives in trees and shrubs (not grasslands), usually near water, and is most abundant in the Ozarks (not limited to northern Missouri).
Adult length: 12 to 20 inches; occasionally to 31 inches.
Declared extirpated from Missouri. If it is ever rediscovered in our state, the most likely place would be in grasslands in our extreme northern counties. The most recent records, dating from 1970 and before, were from scattered counties in the northern half of the state.
Habitat and Conservation
In the northern half of Missouri, this species once lived in grassy habitats, including prairies and pastures. Due to habitat destruction and insecticides, smooth greensnakes have not been recorded in the state for more than 50 years. It has been declared extirpated from Missouri.
This species prefers grasslands. In Iowa, it occurs in grassy, moist meadows, native prairies, and upland grassland habitat surrounding lakes and reservoirs.
In Missouri, the active season of this species presumably lasts from April into October. Most Missouri records are from mid-April into June.
Smooth greensnakes forage actively among grasses and shrubs during the day. At night, they hide beneath logs and boards or within mats of grass and animal burrows.
Their green color is an impressive camouflage; they are almost impossible to see among grasses. This camouflage is enhanced by their behavior of swaying gently along with the windblown grasses.
This species overwinters underground in abandoned mammal burrows, road embankments, and ant mounds. Ant mounds apparently are a preferred overwintering site. They may also overwinter in the burrows of grassland crayfishes.
Food
The smooth greensnake preys on a variety of insects (including caterpillars, crickets, and grasshoppers), slugs, snails, earthworms, and spiders.
Status
A Missouri species of conservation concern; listed as extirpated from Missouri since it has not been seen in more than 50 years. Its nearest secure populations are to the north and east of Missouri.
In Missouri, the last confirmed observation of this species was from 1970 in Harrison County, in northwestern Missouri.
The destruction of its grassland habitat and the use of agricultural insecticides are primarily responsible for the decline of this species in Missouri.
Although the smooth greensnake is presumably gone from the state, this secretive species is known to occur in several Iowa border counties. Therefore, small relict populations may still persist in Missouri. Besides keeping a watchful eye for this bright green snake in extreme northern Missouri, additional efforts are needed to determine this species’ status in our state.
Across its overall North American range, this species frequently occurs in small, isolated populations and appears to be declining in many places.
Life Cycle
Smooth greensnakes normally mate in the spring but also breed in early autumn. Females lay eggs in rotten logs and stumps, mounds of decaying vegetation, leaf litter, sawdust piles, and mammal burrows. More than one female may deposit eggs in the same nest site. There may be 3–15 eggs per clutch, with an average clutch size of 6.
Egg-laying and incubation time varies greatly with this species. Gravid females retain the developing eggs for a period during early summer, and the eggs consequently hatch soon after being laid; this is not the case for most other North American snake species. Incubation period is generally less than 1 month but can be only a few days after the eggs are laid.
In captivity, a smooth greensnake lived to slightly over 6 years of age.
Human Connections
When humans apply pesticides to destroy insects, they often indirectly harm populations of the animals that feed upon insects, either by indirect poisoning or by reducing the prey available to them. For this reason, and because humans have destroyed, altered, or fragmented its habitat, this species has apparently entirely disappeared from our state. But we can still hope to rediscover them.
This slender snake specializes in eating insects. In a real way, it provides us a natural, nontoxic pest-control service.
This harmless snake struggles to escape, but it seldom attempts to bite when handled.
The genus name, Opheodrys, is from Greek roots and means "tree snake." The species name, vernalis, is from the Latin word for "springtime."
Ecosystem Connections
Animals that prey on insects serve as a check on the populations of the insects they eat.
Hawks, herons, raccoons, foxes, other snakes, and even spiders eat this small snake.
The green color and accompanying instinct to sway along with breezes function as camouflage. The camouflage may help this species to be a more stealthy hunter, and it may also help it to evade being preyed upon itself.
As this snake shows, camouflage can be more than coloration. Other animals that use camouflage movements (swaying along with the breeze) include the American bittern (a type of heron that lives among tall grasses in marshes) and the northern walkingstick (a twig-shaped insect that lives among the leaves and outer branches of trees).
