New Jersey warning about venomous snakes. Here's what to know.

WATCHUNG, N.J. -- New Jersey wildlife officials are warning residents to watch out for northern copperhead snakes after one was spotted in Somerset County.

Northern copperhead snakes are one of two venomous snake species found in New Jersey and should never be touched, according to New Jersey Fish and Wildlife.

They can be easily camouflaged in leaves on the ground.

What does a northern copperhead snake look like?

According to an excerpt from the "Field Guide to Reptiles and Amphibians of New Jersey," the northern copperhead snake can be 22-53 inches long.

"The Copperhead, with its red-brown ground color and darker crossbands, is easily camouflaged in the leaf litter of a forest floor. The dark brown, saddle-shaped crossbands are narrow on top and wide on the sides. The Copperhead has scattered dark spots in lighter areas. As the name indicates, the triangular, unmarked head is a copper color. The young have a yellow tail tip. Scales are weakly keeled; anal plate is single," the guide states.

It's key features are a coppery-red head, dark "hourglass" shaped bands that are wider on the sides, a shovel-shaped head, vertical pupils and facial pit, and weakly keeled scales.

Where northern copperhead snakes have been found in N.J.

The northern copperhead snake "favors rocky, wooded uplands and wooded wetlands; may be found hiding in rotting woodpiles, or perfectly camouflaged on leafy forest floor. The Copperhead will den with other species of snakes in the winter, particularly the Timber Rattlesnake," according to the New Jersey field guide.

They like "rocky talus slopes and forest habitats" in northern New Jersey, primarily in Sussex, Warren, Hunterdon and Passaic Counties.

Northern copperhead snakes are active from May through October, according to New Jersey wildlife officials.

What to do if you see a venomous snake in New Jersey

A northern copperhead snake was spotted recently in Watchung, near Winter Lane and Scott Drive, officials said. A large snake also caused a stir in Rockland County, New York this year.

If you see a venomous snake in your area, call the New Jersey Department of Environmental Protection's hotline at 1-877-WARN-DEP (1-877-927-6337). If you are bitten by a venomous snake, you should call 911 immediately.

Click here for tips on what to do and not do if you see a snake.