66 THE HABITS AND BIONOMICS OF THE HOUSE-FLY 



The following records taken from a "fly census" that was made 

 in 1907 may be taken as illustrative of the proportional abundance 

 (if the different species in different situations; although the num- 

 bers 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. doniestica, 11 "5 per cent. F. canicularis, and the rest were 

 other species such as S. calcitrans, Muscina stabulans, C. evythro- 

 cephala, and Anthomyia radicum. These figures are comparatively 

 small, but are representative of the average occurrence, as I have 

 observed, of the different species. 



In a collection of flies caught in rooms where food supplies 

 were exposed in different cities of the United States, Howard 

 (1900) found that out of a total of 23,087 flies, 22,808 or 98-8 per 

 cent, were Musca domestica and of the remaining 1"2 per cent. 

 F. canicularis was the commonest species. Hamer (1908) found 

 that more than nine-tenths of the flies caught in the kitchens and 

 " living rooms " of houses in the neighbourhood of depots for horse- 

 refuse, manure, etc., were M. domestica. In a further report Hamer 

 gives more details as to the different species that were found. 

 In one lot of 35,000 flies caught on four fly papers exposed 

 in similar positions, 17 per cent, were F. canicularis, less than 



1 per cent, were C. erythrocephala and considerably less than 1 per 

 cent, were Muscina stabulans ; whereas of nearly 6000 flies caught 

 in another situation in four fly balloons 24 per cent, were 

 F. canicularis, 15 per cent, were C. erythrocephala and nearh" 



2 per cent, were M. stabulans. In his report for 1909 he gives an 

 excellent diagram illustrating the seasonal prevalence of the six 

 principal genera of flies caught in houses. 



Niven found that out of 8553 flies caught in six different 



