Physical Characteristics Adult Northern two-lined salamanders, 6.4 to 12.1 cm in length, are characterized by a broad stripe stretching from head to tail along their slender bodies. The stripe, bordered on both sides by narrow black lines that may separate into dashes along caudal regions, ranges in color from yellow to greenish yellow or tan. Medially, the stripe may be marked with a row of dark spots. Yellow or mottled pigmentation extends down the sides, each with fifteen to sixteen costal grooves, and small legs to the yellow belly.
Sexual dimorphism exists among males and females, but is more pronounced in the breeding season.
Young and older Eurycea bislineata larvae differ from adults in coloration and markings. The yellowish ground color of young larvae is spotted with gray or brown on the head and back. Young larvae also possess one dark irregular stripe containing six to nine light spots along upper regions of each side. A secondary row of spots may develop as the larvae age. Adult diets consist of insects such as beetles, mayflies, and springtails, as well as spiders, pillbugs, and centipedes.