In 1932, severe defoliation of alders (Alnus rubra Bong.) in Stanley Park, Vancouver, drew attention to a sawfly, Hemichroa crocea Geoff., which was responsible for the damage. More extensive infestations have occurred during the past six years on alder in the lower Fraser Valley. In Europe, the species has been known for a long time as a defoliator of various species of alder (W. Konow, Chalastogastra, 1901-1905). In 1936, R. Glendenning of Agassiz, B. C. said in a letter that he had found the larvae causing some injury to cultivated filberts.