1913 ErNTOMOLOGICAL SOCIETY. 87 



NOTES ON SOME FOREST INSECTS OP 1912. 

 J. M. SwAixE, Assistant Entomologist for Forest Insects, Ottawa. 



During the season just closing there have heen few serious extensive outbreaks 

 ' of insects in Canadian forests. The Larch Saw-fly has ibeen less injurious in the 

 east, but is extending its western ranges beyond Manitoba and is still very de- 

 structive in Western Ontario, Attempts have been made 'by Dr. Hewitt to colonize 

 the European parasite Mesoleius tenthredinus and the parasitic fungus Isaria fari- 

 nosa at several points in Quebec and Ontario and in the Riding Mountains, Mani- 

 toba. With such leaf-feeding insects, widespread over great forest areas, the in- 

 troduction of sidch foreign parasites and assistance in the distribution of native and 

 esta/blished species seems to offer the only hope for any human influence upon the 

 control. 



The Spruce Budworm, which caused so much alarm for several years in Que- 

 bec forests, has been on the whole much less in evidence this season. We know of 

 no instance in which its injury was followed 'by extensive Bark-beetle attack. 



The control of such species as the Larch Sawfly, Spruce Budworm, Brown-tail 

 and Gipsy Moth and the European Scourge, the Nun Moth, presents . tremendous 

 difficulties. In European countries, where the forests are policed by a large body 

 of trained foresters, control measures may be attempted that are not to be even 

 considered in our immense area. There appears to be but one way in which we 

 can influence the extent of the ravages. This is by increasing the numbers in an 

 infested region, of the active parasites which effectively prey upon the pests. With 

 an introduced pest, natural parasites, if not brought with it, may perhaps be suc- 

 cessfully introduced and colonized. It is conceivable that in future years parasites 

 will be obtained in quantity in infested districts to be shipped to distant sections of 

 our forest area for the control of incipient outbreaks of the same injurious species. 

 The present status of the Larch Saw-fly in Canada offers an illustration. So far 

 as the relations hetween this species and its natural control factors have been studied 

 in Eastern Canada, it appears that Ceolopisthia nemuticida plays a most important 

 part. We have no record of this parasite from Manitoba, where the Saw-fly is now 

 widespread. There is a very serious outbreak in Western Ontario, towards the 

 Manitoba boundary. Whether the parasite is there or not we do not know; but, 

 apparently, as the outibreak is not under control, its numbers are not yet great. 

 We should be justified in attempting extensive introduction of Coelopisthia into 

 many sections of Manitoba in an endeavour to check the western spread of the 

 pest, provided, of course, supplies of parasites could be obtained. 



This distribution of native parasites has already been tried in England and 

 Europe ; and, in connection with other insects, has heen attempted in various places 

 in the United States. 



We know that this Saw-fly at times sweeps over extensive areas in America, 

 and is not controlled by any parasites or any factors whatever. The outbreak at 

 times ceases only with the death of the trees. We cannot depend, therefore, upon 

 native species for permanent control, unless we can materially influence their dis- 

 tribution. 



With such an immense area of forest we shall probably usually have Saw-fly 

 outbreaks just under control, with a plentiful supply of parasitized cocoons in cer- 

 tain parts of the country, while in other parts outbreaks will he in their incipient 

 stages. 



