10 Oct. 1917.] The House Fly. 629 



intestine proper, where the food is digested. Most of the food "taken 

 goes first into the crop, which has a twofold function. In the first 

 place, it is used as a reservoir, where a reserve of food may be stored 

 for a time of scarcity ; and, secondly, it enables the fly to secure rapidly 

 and carry off food sufficient to last it several days, the liquid from 

 the crop being used to moisten and dissolve such dry foodstuffs as sugar. 

 Having feasted, the fly exudes fluid from the tip of the proboscis; the 

 cause of this may be that the crop has been distended to an uncomfort- 

 able degree, and that it obtains relief by regurgitation of food. But 

 little reflection upon this habit, with the knowledge of the fly's equal 

 partiality for sputum, excrement, &c., and the common human foods, 

 and that it passes from one to anotlier in rapid succession, make even 

 the least thoughtful better able to appreciate the danger of infection 

 and pollution of sugai'. milk, meat, &c. The feet of the fly are of the 

 nature of adhesive pads, and are ideal vehicles for the distribution of 

 pathogenic organisms. The insect's excrement, which may be voided 

 50 times a day, is a further source of infection. 



The following facts are gathered from a work by C. Gordon Hewitt, 

 D.Sc, F.R.C.S. : — " Among the organisms menacing human life and 

 proved to be distributed by flies are typhoid bacilli, which may remain 

 alive in the intestine of the fly for six days; and flies affected with this 

 bacilli may infect material on which they walk for at least two days. 

 Similar results have been observed in respect of the meat-poisoning 

 bacilli. Ten days or more after infection, tubercle bacillvis has been 

 found in the intestine of the fly. Spores of the anthrax bacillus have 

 been proved to remain on the legs and in the intestines of flies for at 

 least twenty days. Excrement passed fourteen days subsequent to in- 

 fection has been found to contain living spores; and if (he fly died 

 with the spores in or upon their bodies, these spores might remain alive 

 for months, or even years." 



Clean flies will infect themselves by sucking at the vomit sjiots and 

 excrement of their infected fellows, and as flies can rapidly travel con- 

 siderable distances, infection may be carried from a distant source. 

 Experiments have been conducted in which flies were, within 35 minutes, 

 recaptured 1,700 yards from the point of liberation. 



In "Victoria during the year 1915, the deaths of 71 infants were 

 attributed to intestinal troubles, and 74 per cent, of these deaths occurred 

 during the five months between December to April, during which period 

 of the year the fly is always most active. During the other seven months, 

 when the pest is inactive, only 26 per cent, of the deaths occurred. The 

 pravalence of ophthalmia is almost entirely due to infection by flies, and 

 the preponderating number of cases among infants compared with adults 

 is due to the helplessness of the former to protect their eyes from attack 

 by flies. 



Speaking of the spreading of disease by flies, Dr. Hewitt says: — 

 "Malaria in India alone claims one million victims each year; the 

 disease being conveyed by the mo.squito. Plague, which has created 

 terrific devastations each year, was found to be transmitted by the flea. 

 Sleeping sickness is caused by the tse-tse fly. Lice transmit the causa- 

 tive organism of typhus. The stable fly is suspected of being the 

 disseminator of infantile paralysis; but, of all revelations, perhaps none 



