BREEDING HABITS OF LESSER HOUSE-FLY 189 



lines. In the female it is of a lighter grey, and the three 

 longitudinal stripes are consequently more distinct. The abdo- 

 men of the male F. canicidaris is narrow and tapering compared 

 with that of M. domestica. It is bronze-black in colour, and each 

 of the three abdominal segments has a lateral translucent area, so 

 that when it is seen against the light, as on a window-pane, three 

 and sometimes four pairs of yellow translucent areas can be seen 

 by the transmitted light. In the female the abdomen is short 

 in proportion to its length and is pyriform in shape, greenish or 

 brownish-grey in colour with a golden attachment. The average 

 length of the species is 5*7 mm. 



Fig. 82. Antennae, (a) of F. canicnlaris, (/;) of M. domestica. 



Great disparity in the proportion of males to females is found 

 in this species as it occurs in houses. Hamer showed, in 1909, 

 that the males constitute fi'om 75 to 85 per cent, of the total 

 flies of this species caught in balloon fly-traps and on fly-papers. 

 This, however, does not indicate a disparity in the proportion 

 of males to females in the species, as I have found that the 

 females are more commonly found out-of-doors, e.specially in the 

 neighbourhood of the breeding-places. 



The breeding habits of this species are somewhat similar to 

 those of the house-fly, M. domestica. The larvae breed in 

 decaying and fermenting vegetable and animal matter, and also 

 in excrementous matter. In 1848 Heeger recorded it as living 

 in the caterpillars of Epischnia canella^ ; Roth found them in 



1 Larvae of F. canicidaris were found feeding on the body of a dead caterpillar 

 (Xylirni sp.) in a breeding cage in my laboratory on September 5th, 1913. 



