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65 
the manure resulted in decided relief from house flies in the neighbor- 
ing house. Where it is possible, thei, to build such a receptacle, this 
course is advised. 
All stables should be kept scrupulously clean. The stable of the 
Department of Agriculture, in which observations had been made, is 
kept very clean and probably very few flies breed there. It isswept out 
and washed out frequently. The horse droppings are removed care- 
fully each twenty-four hours and placed in a pile beside the stable, 
whence, at intervals of a week or more, they are removed to the com- 
post heap some distance away. The daily pile attracts hosts of flies 
and is soon swarming with larve. 
In order to ascertain the numbers in which house-fly larve occur in 
horse-manure piles, Mr. Busck, at the request of the writer (and, by the 
way, Mr. Busck has assisted in all of the experiments), took a quarter 
of a pound of rather well-infested horse manure on August 9, and 
counted in it 160 larvee and 146 puparia. This would make about 1,200 
house flies to a pound of manure. This, however, can not be taken as an 
average, as no larve are found in, perhaps, the greater part of the ordi- 
nary manure pile. Neither, however, does it show the limit of what can 
be found, since Mr. Busck counted about 200 pup in less than one cubic 
inch of manure taken from a spot 2 inches below the surface of the pile 
where the larve had congregated in immense numbers. 
There are no other horse stables in the immediate vicinity of the 
Department of Agriculture, and it is reasonable to suppose that the 
treatment of this temporary pile every third or fourth day by spraying 
it with kerosene, pouring on water and turning it with a fork, will have 
an appreciable effect on the number of house flies which, during every 
summer, annoy the officials of the Department. This treatment should 
be begun early in the season, since, as with other insects, it is immensely 
more effective to kill a single individual in the spring than at a later 
season of the year. This is plainly shown from an estimate which the 
writer has made, to the effect that from a single overwintering female 
house fly there may be descended in the course of the following 
Summer a number of individuals mounting into the sextillions. For the 
person who is curious about statistics of that sort it would be interest- 
ing to estimate the length of a line of flies of this number, or the weight 
of this number of flies, and so on. 
It seems to the writer that many persons may consider it worth while 
to go to the slight trouble needed to treat manure piles in this way and 
to keep their stables clean. Not only the house fly but the biting 
stable fly (Stomoxys calcitrans) will be killed in this way, and the writer 
is not at all sure, in view of the possibilities in the way of transmis- 
sion of disease by both the house fly and the stable tly, that it would 
not be advisable for city boards of health to pass regulations insisting 
upon greater cleanliness of stables and such a treatment of manure as 
has been described. 
11930—No, 10——5 
