The life cycles of the Pacific Northwest native Laricobius nigrinus Fender, eastern North American native L. rubidus LeConte, and the Japanese native hemlock woolly adelgid (HWA), Adelges tsugae Annand, were documented in southwest Virginia to determine their temporal synchrony. A plantation of eastern hemlock, Tsuga canadensis, saplings were established in 2001, infested with HWA, and 252 adult L. nigrinus were released in Nov. 2003. In Sep. 2005 - Jul. 2006, adult L. nigrinus (F2 generation) and L. rubidus were collected with beatsheets at 2-wk intervals and their abundance was recorded by species. Hemlock foliage clippings infested with HWA were collected from the trees at 2-wk or 1-wk (late Feb. - May) intervals. The foliage clippings were examined microscopically and the numbers of HWA and Laricobius spp. immature stages (F3 for L. nigrinus) were recorded. Beatsheet sampling collected 193 L. nigrinus from 3 Nov. (2005) - 10 Apr. (2006) and 383 L. rubidus adults from 3 Nov. (2005) - 8 May (2006). The appearances of Laricobius spp. adults coincided with HWA sistens generation development after aestival diapause, and continued through sistens oviposition of progrediens eggs. Laricobius spp. eggs and larvae (sum=329) were collected from 24 Feb. - 8 May (2006), which matched the beginning and end of sistens oviposition. Laricobius nigrinus and L. rubidus were highly synchronized with acceptable HWA prey stages. The adaptability of L. nigrinus to a new environment and L. rubidus to a new host suggests a high potential for effective biological control of HWA.