l8 FLIES FOUND IN HOUSES 



In the earlier part of the year, however, F. canicidaris is the 

 most common species. For example Austen (1911, p. 12) records 

 that in the kitchen of a house in Leeds fly papers in May, June 

 and July caught 381 specimens of F. canicidaris and only 48 

 specimens of M. doniestica. 



Descriptions of common honse frequenting flies. 



The figures illustrating each species have been very carefully 

 drawn from accurately identified specimens so as to emphasize the 

 principal features. In species showing marked sexual differences 

 both males and females are illustrated. In the case of those 

 species in which the sexes closely resemble each other, but can 

 be easily differentiated by the space separating the compound 

 eyes, a sketch of the head of the sex not figured is given also. 

 In each species the antenna is illustrated as seen when the 

 specimen is viewed from the side. In most cases the figure 

 shows the fly magnified three times, but for the sake of clearness 

 a life-sized sketch of the insect in the resting position is added. 



In all cases the fly is described and illustrated as seen under 

 a low power (F. 55) of a Zeiss binocular dissecting microscope 

 with the head pointing towards the window. This uniform 

 method has been adopted because in many species the markings 

 appear totally different, when viewed from various directions. 



No attempt has been made to give an exhaustive description 

 of each insect, only the most important and characteristic features 

 being mentioned. Moreover, those features, such as the venation 

 of the wings, which can be clearly appreciated from the figures, 

 have been omitted in the descriptions. 



It is hoped that with the aid of the illustrations and 

 descriptions the species mentioned may be approximately 

 identified, but it should be clearly understood that the aid of 

 an entomologist, interested in the Diptera, is necessary in order 

 to make certain of identification, especially in doubtful cases. 



Such of the habits of the adults as seem to be of interest and 

 importance in relation to the possibility of the distribution of 

 disease-producing bacteria are shortl}' described, and a brief 

 account of the life-history is added in most cases. The larval 



