Studies on the biological control of the spruce budworm, Cacoccia fumiferana Clemens, in southeastern Manitoba and northwestern Ontario

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Lejeune, Raymond Rene
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The spruce budworm, Cacoecia fumiferanca is a native insect which has exacted an enormous unestimated toll from the Jack pine forests of southeastern Manitoba and north- western Ontario during the past five years. The history of this present epidemic is somewhat obscure, but it is quite possible that it originated in Michigan or Minnesota. Graham (1925 and 1928) reported two evidently distinct biological races of spruce budworm from Minnesota, one on spruce and balsam and the other on Jack pine. These are apparently the first published records of this insect causing serious defoliation of Jack pine. In all probability this biological race on pine spread northward and westward into Canada. During 1938 this infestation increased to record proportions in the Jack pine regions of southern Manitoba and northwestern Ontario. Epidemic conditions now obtain throughout this country eastward to Port Arthur and south to Fort Frances and into Minnesota...