Forest Insect Conditions in the Riding 

 Mountains, Manitoba^ 



By J. M. Swaine, Assistant Entomolog ist for Forest Insects, C.E.F., Ottawa. 



During May of this year the writer influencing its control is in the intro- 

 visited the Riding Mountain forest duction and distribution of its para- 

 reserve, Manitoba, with the objects of site and fungus enemies. Its young 

 introducing European parasites of or larvae feed upon the larch leaves 

 the larch saw-fly and studying the like caterpillars, and strip and kill 

 forest-insect conditions of the region, the trees when present in large num- 

 The weather was excessively wet and bers. Although not yet destructive 

 cold throughout the month. On the in Northern and Western Manitoba, 

 upper plateau there were practically the saw-fly has committed serious rav- 

 no buds started before the end of ages to the larch, in recent years, 

 May, and insects were nearly all still throughout Western Ontario, 

 in hibernation. Bark-beetles are present in the re- 

 in view of the rapid western spread serve in great numbers in fire-injured 

 of the larch saw-fly, its great devasta- timber and slash from cuttings. Aside 

 tions throughout Eastern Canada, and from the larch saw-fly these beetles 

 the value of the larch to western are the chief insect danger for the 

 farmers, the Entomological Division future. They are small black, or dark 

 attempted the colonization in Mani- brown, hard-shelled beetles, whiek 

 toba of the European parasite of the excavate tunnels and deposit eggs in 

 larch saw-fly, Mcsolcius tenthredinis. the inner bark of living or dying 

 This ichneumon has been particular- trees. The grubs which hatch from 

 ly efficient in controlling the saw-fly the eggs feed upon the bark, often 

 in Great Britain. Through the ef- cutting individual mines. They pu- 

 forts of Dr. C. G. Hewitt a large sup- pate in the ends of these larval mines, 

 ply of parasitized cocoons of the saw- and after maturing to the adult form, 

 fly was obtained from England. These eat their way out through the bark, 

 were planted in two larch swamps in leaving small round holes like shot- 

 the Riding Mountains, east of Clear holes. Some species are the most de- 

 Lake. The abnormal lateness of the structive of all forest insects, 

 season this year was unfavourble to Only a limited amount of cutting 

 the attempt, but effective results are is allowed in the reserve, and this is 

 hoped for. It is important to note chiefly in fire-swept areas. There 

 that the parasitic fungus of the saw- were several considerable burns in the 

 fly, Isaria farinosa, was introduced spring of 1911, and in these the bark- 

 in the same cocoons. beetles were present in spruce and 

 The larch saw-fly, Nematus erich- pine, in immense numbers. There 

 sonii, is now widely distributed in were no fires of importance in the 

 the larch of Manitoba. In the Rid- reserve this spring, and consequently 

 ing Mountain forest reserve, and in little cutting of green timber. There 

 the Spruce Woods forest reserve it is danger of an outbreak of bark- 

 is abundant, although not yet particu- beetles of the genera Dendroctonus 

 larly destructive. It is without doubt and Polygraphus in the neighbour- 

 spreading to the west and north, and hood of these 1911 fire areas. One 

 will ultimately extend wherever the species of these {Dendroctonus mnr- 

 larch is found. . The only hope of rayanae Hopk) has already destroy- 



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