The pupa is often white in the early stages, but gradually turns black - the color of the adult. The egg is white and slightly oval and about 0.8 mm long. Adult beetles are active primarily from May through August, but localized weather and microclimatic conditions can affect beetle activity. Adult beetles may live as long as 2 weeks. Females lay groups of eggs in bark crevices of weakened, dead or dying trees, or logs in which the cambium is still moist.
Eggs usually hatch within a week.
Development from egg to adult may take 1 to 2 years. A mature larva needs exposure to winter temperatures before pupating. From eggs laid in June, larvae mature in late summer, overwinter in a pre-pupal chamber in the outer bark, and pupate the following spring. From eggs laid during July or August, immature larvae overwinter in the inner bark, mature in the second summer, spend the second winter in the outer bark, and pupate the following spring. Small oval holes in the bark, about 3 mm in diameter, indicate that development is complete and beetles have emerged.