1919 ENTOMOLOGICAL SOCIETY. 33 



has often led to misunderstanding, is that of presuming because an insect occurs 

 across the continent, that it is therefore identical in its life habits throughout its 

 range. As a matter of fact very few are. This was brought prominently to my 

 notice during some recent studies in white grubs {Lachnosterna spp). In the east 

 and southward through Indiana, where Mr. J. J. Davis has made such a thorough 

 study of these insects, the life cycle is usually three years, whereas in southern 

 Manitoba it is four years. Now supposing we had studied only the eastern habits 

 and applied them to the west, we should be a year out in our prognostication. It 

 is of interest to note here that I found a similar variation in the life cycle of tiger 

 beetles (Cicindela) as compared with habits worked out by Professor Shelf ord 

 at Chicago. I am also of the opinion that we shall find the habits of some of 

 our wireworms to differ in the same way. Another example may be found in the 

 Hessian Fly, though in this case it is simply a matter of a reduction in the number 

 of generations. 



In the past there was a general tendency to supply the habits of old world 

 insects to those of the new and occasionally we find an instance where this is still 

 marring our progress. An example of this occurs in a well known pest of the 

 Prairie Provinces, namely, the Western Wheat-stem Sawfly, Cephus cinctus. This 

 insect was originally confused with the European Cephus pi/gmcnis, consequently 

 as no further studies seemed necessary at that time, the old remedies were recom- 

 mended, and are in some instances still, in spite of the fact that every effort has 

 been made to show that they do not apply. 



It might be asked, what are the outstanding differences that so alter the habits 

 of identical insects. There are several, but the chief ones are those of climate; 

 greater extremes of temperature, especially on the downward trend in winter, 

 and less precipitation. I have already shown how lack of snow is responsible for 

 the destruction of a large percentage of our Colorado potato beetles. We had 

 another remarkable instance of this last Mdnter, which in the vicinity of my home 

 near Treesbank, Man. was responsible for a total extinction of the species. Thua 

 it will be seen that our frosts are of some value after all. Incidently I may 

 mention that these same invigorating winters have proved an important factor 

 in restricting another invader, namely the brown rat. The chief inclination of 

 our climate, however, is to prolong the life cycle and this seems a general rule 

 where native species are concerned. 



The study of climate and meteorological changes in relation to animal life 

 is a most interesting one and also important. Occasionally even a native insect 

 gets caught by abnormal conditions of weather of which we had an instance last 

 spring when a serious lepidopterous tree pest was reduced to quite insignificant 

 proportions through the actions of a belated storm cutting off the food supply. 

 I remember what promised to be another instance some years ago during a severe 

 locust outbreak. The young hoppers had been hatched aliout two weeks when along 

 came a severe snow storm accompanied by frost. Naturally the prophets predicted 

 a total extermination of the' plague, but like some well-known weather prophets 

 their predictions were not verified, in other words, the locusts were in no way 

 affected. 



Since we do not grow apples to any appreciable extent, nor are much troubled 

 by other fruit pests, we are able to concentrate largely upon cereal insects and 

 those attacking root or vegetables. The field for this work is a very large one 

 as can well be imagined when it is known that Saskatclicwan alone had more than 

 22,000,0-00 acres under crop in 1918. 



3-E. 



