(109) 



350 



C. GORDON HEWITT. 



suburban houses and country houses and cottages, I find that 

 in the former it is by far the commonest house-fly. But 

 whereas M. domes tica may be almost the only species in 

 warm places where food is present, such as restaurants and 

 kitchens, in other rooms of houses Homalornyia cani- 

 cular is, the small house fly, increases in proportion and 

 often predominates ; occasionally one may find it to be 

 commoner than M. domestica. In country houses the 

 proportions vary by the intrusion of Stomoxys calcitrans, 

 which I have often found to be the dominant species. In a 

 certain country cottage, out of the several hundreds captured, 

 S. calcitrans formed 50 per cent, of the total, the rest being 

 chieflyH. canicularis together with Anthomyia radicum, 

 whose larvae, as I have shown (1907), breed in horse-manure 

 with those of M. domestica. The following records taken 

 from a " fly census " that was made in 1907 may be taken as 

 illustrative of the proportional abundance of the different 

 species in different situations ; although the numbers of these 

 records are small the proportions are more obvious. 



Out of a total of 3856 flies caught in different situations, 

 such as restaurants, kitchens, stables, bedrooms and hotels, 

 87'5 per cent, were M. domestica, 11*5 per cent. H. canicu- 

 laris, and the rest were other species such as S. calcitrans, 

 Muscina stabulans, C. erythrocephala, and Antho- 

 myia radicum. These figures are comparatively small, but 



