34 LIFE AND HABITS OF DOMESTIC FLIES 



the proboscis, and the fly then uses her front legs to 

 clean her face. In consequence her legs become 

 covered with the food too and with any germs it may 

 contain, and she uses the hind legs to clean the front 

 ones, and then they are all covered with the food and 

 its germs. But the fly likes to live in the midst of 

 plenty, and the more filthy the food she has sticking to 

 lier mouth and legs the better she enjoys it. The germs 

 like it too, for the fly never has a bath. It is a grand 

 dirty life for all concerned. 



It can be readily understood how disease germs live 

 and multiply on these sticky surfaces, entangled with 

 the fly's food on its legs, among the hairs and bristles, 

 as well as on the mouth-pads and proboscis. But there 

 is no doubt that germs are swallowed by flies, and can 

 and do multiply within the bowels of the insects. The 

 fly's internal digestive apparatus is very simple. There 

 is a throat winding up the proboscis, a long gullet lead- 

 ing to the stomach and intestines. There is also a crop 

 connected with the gullet by a long tube ; this crop is 

 a large distensible bag where food is stored until hunger 

 requires its digestion. According to Dr. Graham 

 Smith, house-flies after a meal frequently regurgitate 

 drops of fluid from their mouths, and these drops are 

 responsible for the larger marks on the lump-sugar or on 

 the window-pane. The smaller marks are those of excre- 

 tion, fully digested by the fly and passed from the intes- 

 tine, which contains an almost pure nidus for bacteria. 1 

 Thus are fly-specks made. Everything seems to have 

 been disposed by a provident Nature for the germination 

 of germs on and in house-flies. These insects can 

 harbour and foster typhoid and cholera bacilli on their 

 feet, on their mouths and proboscides, and inside their 



1 Bacteria have been found in dry fly-excretioii for a period of six months. 



