A population of the white fir needle miner, Epinotia meritana Heinrich (Lepidoptera: Olethreutidae), infesting white fir, Abies concolor (Gord and Glend.) Lindl., was studied in southcentral Colorado. Adults oviposited from mid-June through mid-August. Eggs were deposited on the concave side of needles, near the base. Larvae hatched in late July and August, then mined needles 1 or more years old before overwintering inside the first or second mined needle. In the spring, each larva mined one or two additional needles before pupating in the last needle during May or June. There was one generation per year.

White firs of all age classes were subject to defoliation, but tops of codominant trees were most heavily damaged. Oviposition occurred most often on 3–5 year old needles and larvae generally did not move to another year’s foliage. Apanteles (Braconidae) was the most prevalent parasitoid observed, causing about 11% larval mortality.