Laricobius nigrinus (Coleoptera: Derodontidae) is an exotic predator that shows promise as a biological control agent of the hemlock woolly adelgid (HWA), Adelges tsugae (Homoptera: Adelgidae). In preparation for its operational release and evaluation, L. nigrinus must be continually reared in large numbers. Previously, our L. nigrinus colony suffered high mortality rates during and following emergence from aestivation because adults become active before HWA resumes development. Two experiments were conducted throughout the spring, summer, and fall of 2003 to examine environmental factors controlling adult survival and diapause completion. In the first study, aestival survival of L. nigrinus and emergence from diapause were tested at 2 moisture levels and 9 constant temperature and photoperiod combinations. The second study examined the effect of a late-season change in temperature and day length on adult survival and their time of emergence. Survival of L. nigrinus was greatest when maintained at a high moisture level and cooler temperatures throughout the summer. Time of emergence was significantly delayed by increasing temperature and day length, and conversely, emergence can be hastened by decreasing temperature at desired emergence time. Temperature appears to be the primary factor influencing time of emergence, and day length a modifying factor. Based on these results, we will modify the environmental conditions at which aestivating adult L. nigrinus are held to synchronize adult emergence with HWA development.