B. C. Entomological Society 



depressions with water, and larvae of Aedes cataphylla are to be found 

 in these pools in great numbers; the majority of tliese emerge during 

 the last week of May and constitute the snow-pool pest. 



The time of the river freshet varies — in 1922 it occurred in tlie first 

 week of June. Mosquito larvae were found in vast numbers in the 

 flooded areas, and most of those that escaped the oilers completed 

 development before the end of the month. Collections of larvae carried 

 out throughout the district showed that the low-lying area to the west 

 and north of the town is mainly responsible for the pest. In some parts 

 of this basin fairly extensive meadows occur, but dense willow growth 

 clothes the remainder. The breeding areas appear to be of importance to 

 some four miles west of the town. 



During the past season oiling was mainly resorted to in dealing 

 with the pest. Four men were employed through May and June to 

 apply oil, and occasional extra help was provided as needed. Oiling 

 occupied some 194 days' labour and about 2,800 gallons of oil were ap- 

 plied ; watering cans and knapsack sprayers were utilized in spreading 

 tlie oil. The whole breeding area was divided into three districts: one 

 man being held responsible for the work in each. Large drums of oil 

 were distributed by truck to various points in each district, and from 

 these points the oil was transported in smaller containers to a number 

 of stations in the breeding areas — a pack pony and a canvas boat were 

 found useful for this. Oil was spread on all water where larvae were 

 found, and, whenever oiling was completed in any one section, patrols 

 were made to ascertain if effective killing had been secured. Coal oil 

 was used alone, as, owing to the cold nights, it was thought inadvisable 

 to use heavier oils. 



A number of the breeding pools were undoubtedly missed owing 

 to tlie difficult nature of the territory involved ; and in some of the more 

 open stretches wind rendered the oil film partially ineffective. In spite 

 of this, however, the rfesults of oiling were very marked, and about 77% 

 control was realized — the town of Banff and the immediate vicinity were 

 rendered comparatively free of mosquitoes. 



After the necessity for oiling was over, the mosquito sqi^ad worked 

 on permanent improvements. A number of ditches were dug to divert 

 small streams feeding various swampy areas. In many parts of the district 

 the willow growth was found to be so dense that penetration was ex- 

 tremely difficult and the work of oiling was greatly retarded ; to mitigate 

 this a large number of trails were cut through these areas and the 

 majority wei-e rendered easily accessible. 



During the season of 1923 the Entomological Branch plan to con- 

 tinue investigations into the mosquito situation at Banff; flight experi- 

 ments will be conducted to ascertain the actual distance from which in- 

 festation is possible ; and it is hoped to secure data regarding the pos- 

 sibility of introducing certain natural control elements, sucli as the 



