63 
FURTHER NOTES ON THE HOUSE FLY. 
By L. O. HOWARD. 
In the article on the house fly in Bulletin No. 4, new series, of this 
oftice, the writer suggested the prompt gathering of horse manure and 
treating it with lime or keeping it in an especially prepared receptacle 
as a means of abating the fly nuisance. This statement was based 
upon the knowledge that nearly all of the house flies which bother us 
in the summer time come from horse stables, and from the idea, not 
based upon exact experimentation, however, that liming the manure 
would destroy the contained larvie. This process is doubtless more or 
less efficacious in cases of the horn fly, which breeds in cow manure, and 
only in cow manure which is freshly dropped. A mixture of lime in 
this case causes such a rapid drying of the manure as to destroy the 
larvee. Actual experiments, however, made during the months of 
August and September, 1897, in Washington show that nothing is to 
be gained from mixing lime with the horse manure pile as a remedy for 
house flies. 
Haperiment 1 (Air-slaked lime).—August 5 eight quarts of fresh 
horse manure, alive with maggots of the house fly, were mixed with 
two quarts of air-slaked lime. On August 7 no larvie were dead, and 
on August 9 very many had hardened into puparia, while the others 
were seemingly as lively as ever. 
Experiment 2 (land plaster).-—On August 6 eight quarts of horse 
manure from the same pile were thoroughly mixed with two quarts of 
gypsum or land plaster. In this case the manure was spread out in a 
large tin pan and exposed to the sun and air. Three days later exami- 
nation showed that most of the larve had hardened to puparia, while the 
remainder were in good condition. None were dead, although the 
manure was found to be very dry. 
Haperiment 3 (gas lime).—August 7 eight quarts of horse manure, 
alive with larve, were thoroughly mixed with two quarts of gas lime 
and spread out in a large tin pan. August 9 most of the larvie were 
found to have hardened into puparia, and none were killed. 
The absolute inefficacy of this treatment was somewhat disappoint- 
ing. Lime was experimented with on account of its cheapness and on 
account of the ease of application. After consultation with the chem- 
ist of the Department it was decided to try experiments with kero- 
sene, since it was considered that an application of kerosene would not 
injure permanently the fertilizing qualities of the manure, but that it 
would, perhaps, have the desired effect of retarding fermentation until 
it should be put into the ground. 
Hxperiment 4 (kerosene)—September 4, 8 quarts of fresh horse 
manure, containing many larvie of the house tly, were spread out as 
before in a tin pan. On this was sprayed | pint of kerosene. lmme- 
diately afterwards 1 quart of water was poured over the manure to 
