REMEDIES AND PREVENTIVES AGAINST MOSQUITOES. 13 
in which water may accumulate for a time. Even a very small 
amount of water will make a breeding place for very many mosqui- 
toes. It is quite possible for a half of a beer bottle to contain enough 
water to give out literally thousands of mosquitoes. The writer 
knows of one instance where a veritable plague of mosquitoes’ was 
traced to a case of empty beer bottles allowed to remain in a back yard 
for some weeks in midsummer. 
There is a possibility that under certain circumstances mosquitoes 
may breed in water accumulating in the troughs of underground-con- 
duit electric railways. There is abundant opportunity for water to 
accumulate in these troughs, but no exact observations upon mosquito 
breeding in such situations have been made. 
Search carefully for all such places, and either abolish the standing 
water by carting away chance receptacles, by turning over vessels, by 
filling in excavations, or by treating other receptacles with a film of 
kerosene, or by introducing fish into fountains and artificial pools. 
DRAINAGE MEASURES. 
Drainage measures really form a part of the consideration of the 
treatment of breeding places. The drainage of swamp areas for 
agricultural or industrial reasons needs no argument. The value of 
reclaimed swamp land for various purposes is well known. The 
drainage of swamp areas primarily in order to improve sanitary 
conditions and to reduce the scourge of mosquitoes which in itself 
often prevents the proper development of nearby regions is in opera- 
tion and needs no argument. Drainage on a small scale for the pur- 
pose of doing away with mosquitoes has been practiced for a long 
time, and in many parts of the country large-scale drainage with mos- 
quito abolition in view is going on, notably in New Jersey and in 
California. Methods of draining can not be entered into in this bulle- 
tin, but it should be pointed out that in case of salt-marsh land the 
operation is inexpensive, and results of great value have been reached 
both in California and in New Jersey. 
DESTRUCTION OF LARVA BY TREATMENT OF BREEDING PLACES. 
While it is obviously best to abolish breeding places in the ways 
mentioned, it often happens that it is not possible to drain, and at 
least as a temporary expedient it becomes desirable to treat the water 
so as to kill the mosquito larve. Many substances have been tried, 
and, aside from certain proprietary mixtures, nothing has given such 
good results as the use of oils. Efforts to find oils that can be used 
to better advantage than petroleum have failed. Common kerosene 
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