(Lacepède, 1789) (cottonmouth)

Habitat: Semi-aquatic, foraging in aquatic and terrestrial environs, and often remaining in wait to ambush prey.
Life History: Females give live birth to 5-11 young in late summer or early fall; some females briefly remain with their young to provide some degree of parental care.
Native Range: Coast plains of Virginia, North Carolina and South Carolina, and in most of the southeastern United States.  Starting in extreme southern Illinois and Indiana the species occurs south along the Mississippi and Ohio River drainages and as far west as Kansas, Oklahoma and central Texas.
Nonindigenous Range: Collected from a pond in Milton, Massachusetts.
Impacts: No impact on native fauna is likely; this snake did not become established.

  (Laurenti, 1768) (tessellated watersnake)

Habitat: Almost any aquatic habitat; basks on land or on tree branches.
Life History: Eight to 25 eggs are laid in moist soil or muck during July.
Native Range: Europe, Asia, and northern Africa. 
Nonindigenous Range: Collected from Norfolk Naval Base, Virginia.
Impacts: Similarity in habits and diet to indigenous Nerodia and Thamnophis, could precipitate competition with N. tessellata if they became established. N. tessellata could also prey upon indigenous fish and amphibians.
Comments: Waif introduction by overseas freight shipments.  In Europe, N. tessellata are commonly kept by snake hobbyists.