HOUSE FLIES. 9 
The number of eggs taid by an individual fly at one time is undoubt- 
edly large, averaging about 120, and a single female may lay 4 
such batches, so that the enormous numbers in which the insects 
occur is thus plainly accounted for, especially when the abundance 
and universal occurrence of appropriate larval food is considered. 
In order to ascertain the numbers in which house-fly larve occur in 
horse-manure piles, a quarter of a pound of rather well-infested horse 
manure was taken on August 9, and in it were counted 160 larvee and 
146 puparia. This would make about 1,200 house flies to the pound 
of manure. This, however, can not be taken as an average, sitice no 
larvee are found in perhaps the greater part of ordinary horse-manure 
piles. Neither, however, does it show the limit of what can be found, 
since about 200 puparia were found in less than 1 cubic inch of 
manure taken from a spot 2 inches below the surface of the pile where 
Fic.6.—The little house fly (Homalomyia brevis): Female at left; male next, with enlarged antenna; larva 
atright. Allenlarged. (Author’s illustration.) 
the larve had congregated inimmense numbers. The different stages 
of the insect are well illustrated in figure 1 and need no description. 
CARRIAGE OF DISEASE. 
In 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 by flies is by no means confined to 
these great temporary camps. In farmhouses in small communi- 
ties and even in the badly cared-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 important elements in the prevention of typhoid. 
In the same way other intestinal germ diseases are carried by flies. 
The Asiatic cholera, dysentery, and infantile diarrhea are allso carried. 
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