Herpwatch McHenry County
Snakes
Eastern Garter Snake
Thamnophis sirtalis
Where to Find: Can be found in a variety of habitats ranging from forests, meadows, marshes, edge habitats, parks, and open lots free of pollution in urban areas.
Key Characteristics: Coloration can be highly variable. Individuals typically have a yellow to gray stripe running down their back, spanning the length of their body. Some individuals lack stripes while others have an additional stripe running down each side of the body from head to tail. These side stripes tend to have two alternating rows of dark spots above, separating them from the back stripe. In some instances, an individual may lack stripes and instead have a dark brown body predominated by darker spots. Dark spots can also be separated by dark red, orange, or brown scales. Bellies can range from yellow to greenish in color. Scales are keeled. Individuals typically reach lengths of 100 cm.
"Eastern Garter Snake (Thamnophis sirtalis)" by Edward Prenzler
Plains Garter Snake
Thamnophis radix
"Plains Garter Snake" by Matthew Ignoffo
Where to Find: Most frequently found in agricultural fields, grasslands, prairies near ponds, marshes, and occasionally in vacant lots.
Key Characteristics: Noticeable black bars on scales of the upper lip. Distinct white-yellow stripe down both sides of the body from head to tail. Markings are similar to that of the eastern garter snake, but are more pronounced and contrasted. Individuals may also have a pair of two light spots on the top of the head. Scales are keeled. Adults may reach lengths of 100 cm.
Redbelly Snake
Storeria occipitomaculata
Where to Find: Usually found in and around moist forests, wooded areas, bogs, and occasionally prairies.
Key Characteristics: The scales of these snakes are keeled. All individuals have a namesake reddish-orange belly. Light colored spots can be found toward the back of the head. Body color is highly variable, ranging from reddish-orange to gray. Most will display a stripe in the mid-back region which runs along the length of the body. Scales are keeled. These are small snakes, usually not exceeding a length of 35 cm.
"Red belly Snake" by Matthew Ignoffo
Dekay's Brown Snake
Storeria dekayi
Where to Find: May be found in a wide variety of habitats including woodlands, prairies, swamps, edge habitat, and many urban locations including parks and empty lots.
Key Characteristics: A dark stripe is located behind the eye. Along the back, dark spots form two intermittent stripes. Body color ranges from a light gray or brown to medium brown. Bellies are typically a faint pink color. Scales are slightly keeled. Adults are small, reaching 25-33 cm in length. Scales are keeled.
"Dekay's brown snake (Storeria dekayi)" by Michael Taylor
Queen Snake
Regina septemvittata
Where to Find: Individuals can be found in and around bodies of freshwater with abundant populations of crayfish. These snakes are usually located under rocks adjacent to streams or in nearby burrows.
Key Characteristics: Yellow stripe runs along each side of the body, slightly above belly, from nose to tail. Body is a dark brown, almost black. Belly is a bright yellow-orange with four dark parallel stripes, two bold and two thin, running the length of the body. Scales are keeled and adults grow to be medium sized, ranging in length from about 40-70 cm.
"Queensnake (Regina septemvittata)" by Nathan Kutok
Smooth Green Snake
Opheodrys vernalis
Where to Find: Common in moist terrestrial habitats including bogs, prairies, marshes, agricultural fields, and vacant lots. They remain close to the ground, rarely climbing, and can be found in grasses and under loose cover.
Key Characteristics: These snakes do not have any distinct markings, but are easily identified by their bright green bodies covered with smooth scales. Bellies are a light yellow. Individuals are gentle and small, usually growing to lengths between 30-50 cm.
"Smooth Green Snake (Opheodrys vernalis)" by Jake Scott
Northern Water Snake
Nerodia sipedon
Where to Find: Streams, lakes, ponds, drainage ditches, and swamps are all common habitat. Individuals spend most of their time basking on fallen logs or rocks lining the banks of freshwater bodies, or sheltering under shore debris. They can also be found swimming along the water's surface during the day.
Key Characteristics: These snakes are very commonly mistaken for copperheads or cottonmouths, even though neither venomous species is native to the county. Individuals have a distinct alternating pattern of light tan to reddish-brown triangles along the sides of the body which turn into bands toward the animal's head. Belly patterns are variable and range from a splotchy yellow-orange, to a yellow-backed series of reddish moon shapes. Individuals are mildly aggressive and should be handled with care. Scales are keeled. They are large snakes, growing to lengths of 70-100 cm.
"Nerodia sipedon" by Kevin Stohlgren
Eastern Milk Snake
Lampropeltis triangulum
Where to Find: A wide range of habitats are suitable for these snakes including fields, woodlands, rocky hillsides, and are also very commonly found inside farm buildings where they hunt for rodents.
Key Characteristics: The eastern subspecies native to the county has drastically muted coloration compared to other related subspecies. Individuals have a light tan body marked with large reddish-brown splotches which are outlined with black. Typically, individuals display a light "Y" or "V" shaped mark on top of the back of their head. Scales are smooth. Adults are medium-sized reaching lengths between 60-90 cm on average.
"Eastern milk snake (Lampropeltis tiangulum)" by Michael Taylor
Western Fox Snake
Pantherophis vulpinus
Where to Find: Usually found in pastures, agricultural fields, woods, and prairies.
Key Characteristics: Body color ranges from pale yellow to light gray. Length of body is covered in an alternating pattern of dark brown spots in three rows which grow smaller toward the belly. Belly is yellow with a checkerboard pattern of dark squares. Juveniles have a distinct dark band between both eyes while adults lack prominent markings on the head. Scales are slightly keeled. Adults are large and vary in length which varies from 90-130 cm.
"Western Fox Snake" by Tristan Schramer
Species Accounts: Illinois Natural History Survey. (2017). INHS Amphibian and Reptile Collection
Illustrations & Species Accounts: Conant, R., & Collins, J. T. (1998). A Field Guide to the Reptiles and Amphibians of Eastern and Central North America (3rd ed). New York, NY: Houghton Mifflin Company.