Reptiles
Smooth Green Snake
Opheodrys vernalis · also called smooth green snakes, grass snake
A smooth green snake is easy to miss even standing right next to it, its bright, uniform green blending almost perfectly into grass and low vegetation. It is also about as harmless as a snake gets, rarely biting even when picked up, and after death its colour tells a strange secondary story, fading to a dull blue-grey as the yellow pigment that once made it green simply breaks down.
Overview
The smooth green snake, Opheodrys vernalis, is a gentle, insectivorous snake of grassland and meadow across southern Canada and the northern and central United States. It hunts caterpillars, crickets, and other soft-bodied invertebrates by day, protected mainly by camouflage rather than any aggressive defence.
Smooth scales, a fading colour
Smooth, unkeeled scales distinguish it from the similarly coloured rough green snake, and its vivid green comes from a combination of structural blue and yellow pigment that fades after death, leaving preserved specimens looking blue rather than green.
Status
Least Concern overall but decreasing in parts of its range, where pesticide use reducing its insect prey has hit local populations especially hard given how narrow its diet is.
Smooth Green Snake: common questions
How can you tell a smooth green snake from a rough green snake?
The most reliable physical difference is in the scales themselves, since the smooth green snake has smooth, glossy dorsal scales lacking a raised central ridge, while the rough green snake's scales each have a distinct raised keel running down the centre, giving its skin a slightly rougher, more textured appearance and feel. The two species also differ somewhat in typical habitat, with the smooth green snake favouring grassland and meadow more than the more arboreal, vegetation-climbing rough green snake.
Why do preserved smooth green snakes look blue instead of green?
A living smooth green snake's bright green colour results from a combination of a blue structural colour produced by the physical structure of the skin and a separate yellow pigment layered over it, and because this yellow pigment breaks down and fades relatively quickly once the snake dies, preserved museum specimens typically end up appearing a dull blue or blue-grey rather than retaining the vivid green seen in a living animal.
Is the smooth green snake dangerous to keep as a pet or encounter in the wild?
No, the smooth green snake is entirely harmless and is widely regarded as one of the gentlest snake species in North America, very rarely attempting to bite even when handled and generally responding to a perceived threat by remaining still, relying on camouflage, or quickly retreating into nearby grass or vegetation rather than displaying any aggressive behaviour.
Why has the smooth green snake declined in parts of its range?
Because its diet depends almost entirely on soft-bodied insects and other invertebrates such as caterpillars and spiders, widespread pesticide use that reduces these prey populations has had an outsized negative effect on smooth green snake numbers in affected agricultural and suburban areas, compounding the more general pressure of grassland habitat being converted to farmland or development across parts of its range.