It feeds on poplars and willows and sometimes on grey alder. The number of rowan, grey alder, trembling poplar and hackberry is relatively high. Rowan, aspen, willow, grey alder, and bird cherry are common in the lower elevations. The larvae of the alder woolly sawfly sometimes cause considerable defoliation to the grey alder. Several species of Lepidoptera use grey alder as a food plant for their caterpillars. Aspen ("Populus tremula"), Goat Willow ("Salix caprea"), and Grey Alder ("Alnus incana").