Eggs are deposited in previously mined needles and near the base of new needles. Larvae migrate on hatching and quickly bore into individual needles that are usually two or more years old. Usually only one larva enters each needle, remains over winter. Feeding is resumed in the spring and migration to new foliage begins. During a year each larva may mine at least five needles.
Pupae remain in last mined needles.
Although defoliation may be severe, growth reduction is the principal effect.