Rowan
Guides
Pristiphora geniculata
mountain ash sawfly, rowan leaf sawfly, Ebereschen-Blattwespe
Pristiphora geniculata is a sawfly species in the family Tenthredinidae, native to the Palaearctic region and introduced to North America. It is a specialized herbivore of Sorbus species, particularly mountain ash (rowan). The species exhibits facultative parthenogenesis and shows pronounced sexual dimorphism in larval development, with females having five instars compared to four in males. In eastern Canada, it typically produces two generations annually, though only one in northern Quebec and at higher elevations in Europe. The species has been the target of successful classical biological control programs using the parasitoid wasp Olesicampe geniculatae.