Adult diets consist of insects such as beetles, mayflies, and springtails, as well as spiders, pillbugs, and centipedes. Adults may also consume other small invertebrates including earthworms and snails. A high dietary overlap exists among the different sizes of larvae which feed continuously throughout the night and day. Reproduction Northern two-lined salamanders reach sexual maturity the first fall, or occassionally, one year after metamorphosis. Fertilization occurs internally after the female collects a spermatophore in her cloaca.
Females tend to guard nests for at least part of the incubation period lasting thirty to sixty days.
Only one female typically guards a nest in cases where multiple females deposit eggs at the same site. Behavior Northern two-lined salamanders exhibit complex courtship behavior. A male uses his head to nudge or poke a potential mate, and encircles the female's head with the front of his body. The male scratches the female's skin with his teeth, possibly allowing secretions from his mental gland to enter the female's bloodstream. It is hypothesized that these secretions may stimulate courtship behavior in the female.