INSECT FAUNA OF HUMAN EXCREMENT 553 



In all 23,087 iiies were examined which had been caught in 

 rooms in which food supplies are ordinarily exposed and which 

 may safely be said to have been attracted by the presence of 

 these food supplies. Of these 23,087 flics, 22,808 were Miisca 

 douiestica., i. c, 98.8 percent of the whole number captured. 

 The remainder, consisting of 1.2 percent of the whole, com- 

 prised various species, the most significant ones being Ilomalo- 

 myia canicular is {\\\^ species ordinarily called the 'little housefly') 

 of which 81 specimens were captured; the stable f^y [Afiiscina 

 stabulans), 37 specimens ; Phora femorata^ 33 ; Lncilia ccesar, 

 18 ; Drosophila a7n^eIophiIa, 15 ; Sarcophag'a trivialis,\.Q.x\ ; Cal- 

 liphora erythrocephala^ seven. Musca domcstica is, therefore, 

 the species of great significance. Homalomyia caniciilaris is 

 important. 3Itiscina stabiilans is of somewhat lesser importance. 

 Drosofhila ampelophila^ as will be shown, is an important form, 

 and had more of the captures been made in the autumn its num- 

 bers would probably have been greater, since beyond doubt it 

 is an abundant species in houses after fruit has begun to make 

 its appearance (say in August and September and on until 

 winter time) in pantries and on dining room sideboards. The 

 Calliphora and the Lucilia are of slight importance not only on 

 account of their rarity in houses but because they are not true 

 excrement insects. Other forms were taken but either their 

 household occurrence was probably accidental or from their 

 habits they have no significance in the disease-transfer function. 



CONCLUSIONS. 



It appears plainly that the most abundant species breeding in 

 or attracted to human excrement do not occur in kitchens and 

 dining rooms, but it is none the less obvious, as will be seen 

 from the detailed consideration of Musca domestica which will be 

 given further on, that while this species under ordinary city and 

 town conditions as they exist at the present day, and more es- 

 pecially in such cities and towns or in such portions of cities as 

 are well cared for and inhabited by a cleanly respectable popu- 

 lation, may not be considered an imminent source of danger, it 

 is, nevertheless, under other conditions a factor of the greatest 

 importance in the spread of intestinal disease. In the account 



