Adults lay eggs in crevasses in the bark. Larvae burrow into the bark after hatching and consume the living tissue of cambium and phloem. This causes death within two years. The average emerging season for the emerald ash borer is early spring to late summer. Females lay around 75 eggs, but up to 300 from early May to mid-July. The borer's life cycle is estimated to be one year in southern Michigan but may be up to two years in colder regions.