An unusual infestation of the pill beetle, Cytilus alternatus Say, occurred in the Provincial Forest Nursery at Gogama in northern Ontario in 1967. Although Craighead (1950) mentions species of Byrrhus, a closely related genus, as pests in nurseries, no previous record of injury to seedlings by C. alternatus could be found. Two incidental collections of C. alternutus, however, had been made previously in Ontario when a few pupae were collected in the Chapleau Forest Nursery in 1965 and a single adult was taken on St. Joseph Island in 1954. Members of the family Byrrhidae derive their common name, pill beetles, from their oval shape and their ability to “retract” their appendages when disturbed.