74 FUNCTION OF CROP 



crop performs two important functions ; (A) it acts, at the time 

 of feeding, as a large receptacle, which can be filled with great 

 rapidity, and which consequently enables a fly which is disturbed 

 within a few seconds of commencing a meal to carry away 

 sufficient food to live on for some days ; (B) when food is 

 abundant the crop seems to act as a reservoir in which material 

 can be stored against a time when food may become scarce." 



CHAPTER VII 



THE HABITS OF ADULT FLIES 



The habits of most of the species of flies which invade 

 houses have up to the present been very insufficiently studied, 

 only those of M. doniestica, F. canicularis and scalaris, and 

 of certain of the blue-bottles and green-bottles having received 

 careful attention. The breeding habits of the various species 

 have already been mentioned, and in dealing with the habits 

 of the adults it may perhaps be most advantageous to consider 

 them under the following headings : 



A. Range of flight. 



B. Outdoor habits. 



C. Indoor habits. 



D. Hibernation. 



E. Habits after feeding, 



F. Experiments on def?ecation. 



A. Range of flight. 



Up to the present few observations have been made on the 

 range of flight though the subject is obviously of considerable 

 importance in relation to the whole question of the carriage 

 of infection by these insects. The experimental investigations 

 about to be quoted have all been carried out with house-flies. 



