HABITS 79 



TABLE 5. Slwzving results in regard to sexes and species in 

 six sweepings from a horse inannre pile on May 18 and 19, 

 1909. 



12 166 4 94 6 71 15 85 II 222 9 116 

 * Excluding very small diptera. 



r/ /54 



TABLE 6. Shozving number of individuals collected in a 



screened diuelling, fune i, 1909. 



M. F. 



House-fly {M. doiiicstica) 86 116 



Ahtsciiia sp. 3 i 



Homalomyia sp. 5 o 



CalUphora i 2 



95 119 



" Table 5 shows that of those flies which frequent both the 

 manure pile and the home, the house-flies compose 90°/o, and 

 that of the total collected, over 95 »/o were females. Thus, it is 

 clear that it is the 'instinct' to oviposit that has mainly attracted 

 these insects to this situation. In fact, fresher parts of the 

 manure pile are often literally white with house-fly eggs in 

 countless numbers. Observations made in the near vicinity 

 of the manure pile proved that certainly the same percentage 

 (over 95 7o) of the flies clinging to the walls of the stable, boxes, 

 and so on, were males." 



" That the sexes in the house-fly are normally about equal 

 in numbers is apparent, inasmuch as of a total of 264 pupae 

 collected indiscriminately and allowed to emerge in the laboratory, 

 129 were males and 135 were females." 



In smaller villages the flies have many opportunities of 

 frequenting especially filthy substances, and in larger towns, more 

 particularly in some of the great cities, many courts and alleys 



