Garter or Ribbon Snake? Check the Tail and the Lip

Striped snakes in damp grass are almost always one of these two, and both are harmless. Separating them is straightforward once you know where to look, and none of it requires handling the animal.

Tail proportion

The best character, and visible in a photograph.

Measure from the vent — where the underside scales change from wide plates to paired scales — to the tail tip. On a ribbon snake that section is roughly a third of the animal's total length. On a garter snake it is closer to a quarter.

Ribbon snakes look noticeably more slender and long-tailed as a result, and once you have seen both the impression alone is usually enough.

The lip scales

Garter snakes have dark vertical bars on the scales along the upper lip, giving a faintly barred look to the side of the face.

Ribbon snakes have clean unmarked white or cream lips with no bars at all, and a distinct white or pale spot just in front of the eye.

That white pre-ocular spot is diagnostic and is often the easiest thing to see in a photograph of the head.

Habitat

Ribbon snakes stay near water — pond edges, marsh, stream banks — and rarely stray far from it. Garter snakes use a much wider range, including gardens, woodland edge and dry grassland, and are the snake most people meet in a suburban yard.

A striped snake well away from water is very likely a garter.

Which scale rows the stripes sit on

For anyone counting scales, the lateral stripe position differs: garter snakes carry it on scale rows two and three counting up from the belly, ribbon snakes on rows three and four.

This is precise and reliable, and it needs a clear photograph or a snake in hand. For most purposes the tail and lip characters get there faster.

Neither is a concern

Both are harmless. Both will musk enthusiastically if picked up, which is unpleasant and not dangerous, and both prefer to leave.

Garter snakes vary enormously in colour across their range — some populations are strongly checkered, some nearly black, some with red flecking — and this causes far more misidentification than the ribbon snake does. Colour variation within a species is one of the main reasons the venomous-snake tests people use fail so often.

When it matters

Rarely, which is worth saying. Neither species poses any risk, so the identification is a matter of interest rather than safety.

The identifications that matter are covered separately: copperhead or water snake and checking your state both address cases where getting it wrong has consequences, and a striped snake in the grass is not one of them.

Why garter snakes turn up in gardens

They eat earthworms, slugs, amphibians and small fish, all of which concentrate in damp gardens. A compost heap is close to ideal: warm, full of worms, and full of hiding places.

They are also among the earliest snakes active in spring, emerging from communal hibernation sites while it is still cold, which is why the first snake anyone sees in a year is usually a garter.

Live young

Both species give birth to live young rather than laying eggs, in late summer. A garter snake found with a noticeably swollen mid-body in July or August is likely gravid, and the litter can be large — a dozen or more is normal and thirty is not unheard of.

The young are miniature versions of the adults, fully independent from birth, and they are what people find in September and mistake for a different species entirely because of the size.