1921 ENTOMOLOGICAL SOCIETY. 29 



covered with a taller and thicker growth of grass. The erection of fences on some 

 of our main ranges, and the close observation of a small, fenced, experimental 

 plot, may help us to find out our best method of improving our cattle ranges 

 throughout British Columbia, and this is the work planned for 1921. 



In conclusion, I would like to express my appreciation to Mr. E. C. Treherne, 

 who materially assisted me in the preparation of this paper, and who was largely 

 responsible for the conduct of the experiments, and for his personal supervision of 

 the general details of the locust studies. 



THE INVASION OF SOUTHERN ALBERTA BY BEET WEBWORMS. 



E. H. Strickland, 

 Entomologist in Charge of Lethbridge Laboratory. 



In the fall of 1919, the second generation of Beet Webworm larvae (Loxostege 

 sticticalis L.) were extremely abundant in several districts in the southern part 

 of Alberta, but since this generation did not appear until September they attracted 

 little attention other than by somewhat impeding trains and by proving an annoying 

 household pest. These larva? migrate m immense armies, prior to spinning their 

 subterranean cocoons, and refuse to turn aside for any obstruction. Hence they 

 may enter houses in vast swarms, while if any irrigation ditch, or even a horse- 

 trough lies in their line of march they will enter it and drown by the million. 



The majority of these hatched from eggs laid on the abundant growth of 

 weeds that sprang up after heavy rains in August, and though they cleared out 

 miles of lambs-quarters and Russian thistle they fed very little on other vegetation. 



In the early spring of 1920 immense numbers of cocoons were turned up on 

 weedy stubble, and from a large number of these that were sent to the laboratory 

 for determination, a few specimens of the parasite Meterous loxostegii were bred. 



By June 6th adults were flying freely, and this flight reached its maximum 

 intensity between the 9th and 20th, when a single light trap on- the Entomological 

 Laboratory at Lethbridge captured an average of 2,000 moths a night. Since this 

 was much in excess of anything seen in previous years, and these moths were 

 almost invariably considered as being " cutworm millers," illustrated press articles 

 were sent out from the laboratory describing the habits of the species and the 

 likelihood of there being large migrations of larva? later in the season. Eggs 

 were not located at Lethbridge on lambs-quarters, which possibly is the exclusive 

 breeding plant in Alberta, till July 12th, but by the 19th a flood of reports were 

 received by phone and letter from points throughout an area of some 3,600 square 

 miles between Lethbridge and Calgary to the effect that migrating larva? were 

 appearing in. enormous numbers and that hundreds of promising gardens were 

 disappearing before their onslaughts. On the 19th of July the district agent of 

 the C.P.R. reported that two trains had been stalled by them on the lines running 

 south from Calgary, and that section foremen were anxious to know what steps 

 should be taken. As a result the whole C.P.R. system in Alberta was 

 circularised that afternoon. Press articles were prepared, and given widespread 

 circulation, but control measures proved somewhat inadequate, inasmuch as the 

 larva? travelled mainly at night-time and gardens were so heavily infested when 

 the ravages were first seen that spraying was of little avail. Paris green certainly 

 killed them, but they were so numerous that they usually destroyed the crop? 



