Biorhiza Westwood, 1840

A Holarctic genus with six species, four of which in the Nearctic Region (Melika & Abrahamson 2002), one - B. nawai (Ashmead) in the Eastern Palaearctic, and another - B. pallida in the Western Palaearctic. All species are

associated with oaks of section Quercus, on which the asexual generation develops in root galls and the sexual generation in bud galls (Melika 2006b).