Larvae are reared on a synthetic diet in 1 oz. ribbed plastic cups. To eliminate the task of placing individual larvae on food, small gauze patches containing 25–40 larvae are placed in the cups prior to emergence from hibernacula. Larvae establish feeding sites between the ribs and are relatively undisturbed by others in the cup until the fifth instar. For maintenance of rearing stock the number of larvae is reduced to six to eight per cup, and they are allowed to pupate in the cups. Up to 100 pairs of pupae are placed in screened cages for adult emergence, mating, and oviposition. When the adults emerge balsam fir foliage is introduced and most of the eggs are deposited on the needles. Needles or twigs with egg clusters are transferred to large dishes the inside of which is painted black. The dish is tightly sealed with parafilm to which small gauze patches are attached and then placed under artificial lighting. The newly-hatched larvae are attracted toward the light and spin hibernacula in the gauze. The parafilm and gauze are sealed in plastic bags for cold storage treatment. By this system up to 10,000 larvae per week are easily produced.A discussion on the selection of rearing stock, rearing conditions, rearing containers, and the use of anti-fungal agents is included in the report.