10 FARMERS’ BULLETIN 679. 
fested manure were covered with'a large screen cage on November 
26, 1913. No adults emerged after December 27 until April 16, 1914. 
and others on May 26, at which time observations were discontinued. 
This showed that the house fly lived in the larval and pupal stages 
for periods of from five to six months. In another case they were 
kept alive in the immature stages from December 16, 1913, to April 
4,1914. This was at Dallas, Tex. 
CARRIAGE OF DISEASE. 
The body of the house fly is thickly covered with hairs and bristles 
of varying lengths, and this is especially true of the legs. Thus, 
when it crawls over infected material it readily becomes loaded with 
germs, and subsequent visits to human foods result in their contam1- 
nation. Even more dangerous than the transference of germs on the 
legs and body of the fly is the fact that bacteria are found in greater 
numbers and live longer in the alimentary canal. These germs are 
voided, not only in the excrement of the fly, but also in small droplets 
of regurgitated matter which have been called “ vomit spots.” When 
we realize that flies frequent and feed upon the most filthy substances 
(it may be the excreta of typhoid or dysentery patients or the dis- 
charges of one suffering from tuberculosis), and that they may sub- 
sequently contaminate human foods with their feet or their excreta 
or vomit spots, the necessity and importance of house-fly control is 
clear. 
Tn army camps, in mining camps, and in great public works, bring- 
ing together large numbers of men for a longer or shorter time, there 
is seldom the proper care of excreta, and the carriage of typhoid 
germs from the latrines and privies to food by flies is common and 
often results in epidemics of typhoid fever. 
And such carriage of typhoid is by no means confined to great 
temporary camps. In farmhouses in small communities. and even 
in badly eared for portions of large cities, typhoid germs are carried 
from excrement to food by flies, and the proper supervision and 
treatment of the breeding places of the house fly become most im- 
portant elements in the prevention of typhoid. 
In the same way other intestinal germ diseases are carried by flies. 
Asiatic cholera, dysentery, and infantile diarrhea are all so carried. 
Nor are the disease-bearing possibilities of the house fly limited to 
intestinal germ diseases. There is strong circumstantial evidence 
that tuberculosis, anthrax, yaws, ophthalmia, smallpox, tropical sore, 
and parasitic worms may be and are so carried. Actual laboratory 
proof exists in the case of a number of these diseases, and where 
lacking is replaced by circumstantial evidence amounting almost to 
certainty. 
