Neodiprion abietis, commonly known as the balsam fir sawfly, is a species of insect in the family Diprionidae.

It is found in North America from Canada to northern Mexico and is phytophagous, feeding on the needles of coniferous trees.

[3] The larva of N. abietis have salivary glands with a lumen that is lined by microvilli and it also has a single layer of epithelial cells present.

Balsam fir sawfly have a pair of diverticular pouches which are used to store terpenoids which they regurgitate as a form of defense.

[1][6] Months later, around June or mid-July, the eggs hatch and the larvae feed immediately on needles of the balsam fir.

N. abietis larvae have optimal development when they are able to feed on different-aged foliage thus allowing for maximization of their resources.

[7][12] Moreover, the balsam fir sawfly are considered to be wasteful feeders because only the outer portions of needles are consumed during the early-instar larvae.

[13] Ecological factors involved in N. abietis outbreaks are increased immigration, female-biased sex ratios, and reduced mortality due to diseases, parasitoids and host-plant effects.

[18][19] The balsam fir sawfly, more specifically third to fifth instar larvae are responsible for defoliation and foliage weight loss in trees.