13 



abundant in country houses in the vicinity of stables in which horses 

 are kept. The reason for this is that the preferred food of the larvae 

 of house flies is horse manure. House flies breed in incredible num- 

 bers in a manure pile largely derived from horses. Twelve hundred 

 house flies, and perhaps more, will issue from a pound of horse manure. 

 Ten days completes a generation of house flies in the summer. The 

 number of eggs laid by each femj^le fly averages 120. Thus, under 

 favorable conditions, the oflfspring of a single over-wintering house 

 fly may in the course of a summer reach a figure almost beyond belief. 

 With an uncared-for pile of horse ma- 

 nure in the vicinity of a house, there- 

 fore, flies are sure to swarm. Their 

 number practicall}^ will be limited 

 only by breeding opportninities. They 

 are attracted to, and will lay their eggs 

 in, human excrement. Under favor- 

 able conditions they will breed, to some 

 extent, in this excrement. They swarm 

 in kitchens and dining rooms where 

 food supplies are exposed. Thej" are 

 found commonly in box privies, which 

 sometimes are not distant from the 

 kitchens and dining rooms. There- 

 fore, with an abundance of flies, with 

 a box privy near b}', or with excre- 

 mental deposits in the neighborhood, 

 and with a perhaps unsuspected or not 

 yet full}^ developed case of typhoid in 

 the immediate neighborhood, there is 

 no reason why, through the agency of 

 contaminated flies alighting upon food 

 supplies, the disease should not be 

 spread to healthy individuals. That it 

 is so spread is not to be questioned. 

 That under the unusual conditions of 

 the army concentration camps in the 

 summer of 1898 it was so spread to a shocking extent has been 

 demonstrated by the army typhoid fever commission. And the remedy 

 is plain. It consists of two courses of procedure: (1) Proper care of 

 excreta; (2) the destruction of flies. 



Measures to be taken to prevent typhoid fever. — On many farms where 

 intelligent people live the old-fashioned box privy has been done away 

 with, and there has been substituted for it some form of earth closet. 

 Where a good earth closet is m operation, and the inhabitants of a 

 farm appreciate the importance of using no other, and where in case 



Fig. 6.— Full-grown larva of Culex— en- 

 larged (author's Illustration). 



