FURTHER NOTES ON THE HOUSE FLY. 
i;y J.. < ». llowAifi). 
Ill the article on the house ll.y in bulletin No. 4, new series, ol' tliis 
office, the writer suggested the i)ronipt <»atherin«^ of horse manure an<l 
treating it witli lime or keeping- it in an especially prepared receptacle 
as a means of abating the Hy nuisance. This statement was based 
upon the knowledge that nearly all of the house tlies 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 larv;e. This process is doubtless more or 
less efficacious in cases of the horn tly, 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 
larva\ Actual experiments, however, made during the months of 
August and September, 1897, in AVashiugton sliow that nothing is to 
be gained from mixing lime with the horse manure pile as a remedy for 
house Hies. 
Experiment 1 {Air-slal'ed lime). — August 5 eight quarts of fresh 
horse manure, alive with maggots of the house tiy, were mixed with 
tAvo quarts of air-slaked lime. On August 7 no larvic were dead, and 
on August 9 very many had hardened into jjuparia, while the others 
were seemingly as lively as ever. 
Experiment 2 {land plaster). — On August G 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 i)an and exposed to the sun and air. Three days later exami- 
nation showed that most of the larvie had hardened to puparia, while the 
remainder were in good condition. None were dead, although the 
manure was found to be very dry. 
Experiment 3 {gas lime). — August 7 eight quarts of horse manure, 
alive with larvie, were thoroughly mixed with two quarts of gas lime 
and spread out in a large tin pan. August 9 most of the larva' were 
found to have hardened into puparia, and none were killed. 
The absolute inefficacy of this treatment was somewhat disap])oint- 
ing. Lime was experimented with on account of its cheapness and on. 
account of the ease of applicajbiou. After consultation with the chem- 
ist of the Department it was decided to try experiments with kero- 
vsene, since it was considered that an application of kerosene would not 
injure i)ermanently 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. 
Experiment 4 {Jcerosene). — September 4, 8 quarts of fresh horse 
manure, containing many larvae of the house Hy, were spread out as 
before in a tin i)an. On this was sprayed 1 pint of kerosene. Imme- 
diately afterwards 1 quart of water was poured over the manure to 
