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ENTOMOLOGICAL NEWS. 



[April, J iS 



males, and the latter only females. It is interesting to note 

 this high percentage of females even in species that do not 

 breed in excrement. Musca domcstica females were about 

 three times as numerous as males, 564 to 197. The same re- 

 lationship was found to hold good when flies were trapped 

 out-of-doors with human excrement for bait, females being 

 in that instance about four times as numerous as males. 1 

 have no data to show the comparative abundance of the two 

 sexes in houses, but it is apparent that as a seeker of filth the 

 female house fly is potentially more dangerous to the human 

 species than the male. For this reason any bait that will at- 

 tract more females than males should be considered more ef- 

 ficient than one which will attract an equal number of both 

 sexes. Several baits were tried with this in view and a com- 

 bination of beer and oatmeal was found the most effective. 



TABLE GIVING DATA CONCERNING FLIES CAPTURED IN PRIVY TRAP EXPERIMENT 

 AT LAUREL, MONTANA, JULY 20 TO AUGUST 21, 1914. 



