14 



THE REPOET OF THE 



No. 36 



who has recently come from the Montana Station to take charge of the Dominion 

 Entomological Laboratory at Lethbridge, constructed a number of traps similar 

 to those in which these large captures were made. Two of these were set out in 

 a badly infested field at Lethbridge, and about six were operated by our assistant 

 Mr. W. Carter with the help of some farmers in the very heavily infested dis- 

 trict around Retlaw, which is about sixty miles to the north-east of Lethbfidge. 

 These traps were set out from the middle of July till September 8th, when snow 

 and frost put an "end to the flight of P. orthogonia. During periods of moon- 

 light, high wind and other unfavourable . weather these traps were not operated. 



Nft^S^C 



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Trap so arranged that the majority of moths will The most suitable type of trap for moth destruction, 

 be retained. 



The Alberta Moth Trap 



The results were disappointing. The largest capture of P. orthogonia at Leth- 

 bridge was 517 males and 17 females, the average per "trap-night" being 84.3 

 males and 2.03 females. The Retlaw traps captured 41.3 males and 3.8 females 

 per "trap-night." Of the total capture of 34,500 specimens of P. orthogonia which 

 were taken in the field by light-traps 94.97% were males. This percentage was 

 very little better than that obtained in 1913. 



"We ! do not know to what extent the males are monogamous in nature, but it 

 would appear that on this factor alone depends any appreciable benefit to be de- 

 rived from light-traps. 



