Eastern Garter Snake Thamnophis sirtalis by Jeff LeClere Status No status assigned in Minnesota. The eastern garter snake is a medium sized Minnesota snake measuring 14 to 48 inches in length. It is non-venomous and some specimens can be less docile than the plains garter snake. The ground color is light brown to black with two alternating rows of black spots.
Some specimens have a lighter background color in which the spots stand out especially well.
There are three longitudinal stripes. The dorsal stripe is usually yellow. The lateral stripes are cream to yellow and are located on the second and third scale rows. There is usually a row of black spots below the lateral stripes. The belly may be white, yellowish, or bluish.