Parasites of Neodiprion pratti banksianae Rohwer in Northern Ontario

Ourbreaks of the jack-pine sawfly, Neodiprion pratti banksianae Rohwer, occur in northern Ontario at irregular intervals. Two independent outbreaks within 50 miles of each other – one on Great Cloche Island (McGugan et al., 1952) which lies in the North Channel of Lake Huron between Manitoulin Island and the mainland, and the other near Nairn Centre, approximately 30 miles west of Sudbury, Ontario – offered an opportunity to study the parasitism of this important defoliator. In 1954, when the study was started, heavy defoliation had been reported for several years in the Great Cloche outbreak, and light defoliation had occurred for one year in the Nairn Centre outbreak. Populations decreased in the Great Cloche area but remained relatively constant at a low level in the Nairn Centre area during 1955 and 1956, when the work was completed.