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14 MISC. PUBLICATION 336, U. S. DEPT. OF AGRICULTURE 
loss by reduction of property values, injury to livestock, expense of 
protective measures, and in other ways. These losses frequently are 
much greater than the cost of mosquito control. ttt 
Nearly everyone is familiar with the efforts made to eliminate 
mosquito-breeding places and with the use of larvicides in antimos- 
quito work. The practical phases of the problem, however, form a 
large specialized subject, and a general summary only will be given 
here, with reference to underlying principles and to the practices and 
materials that have become more or less standardized or are of recent 
development. 
Mosquito SURVEYS 
Mosquitoes have extremely diverse breeding habits, particularly 
in respect to the type of place selected for oviposition. Because of 
this diversity the species to be dealt with and their individual habits 
must be known before control measures can be applied intelligently. 
If the work is undertaken for the control of one of the common 
diseases, such as malaria or dengue fever, the presence of the disease 
itself, in the Southern States at least, indicates a particular species of 
mosquito. A study of the distribution of human cases of the disease 
serves to localize the problem, and a mosquito survey is undertaken 
to aid in developing the plan of procedure. At the same time the 
possibilities of including control measures against purely obnoxious 
species that may be present should not be overlooked. Where relief 
from annoyance is the main object, a thorough species survey is 
necessary to determine what the problem is and the relative impor- 
tance of the different kinds, since more than one species is usually 
involved. Even in coastal areas, where it is known that the salt- 
marsh species are the principal culprits, it is still highly important 
to know whether fresh-water breeders are sufficiently numerous to 
require consideration. 
The surveys are begun by the collection and identification of both 
adult and larval specimens. During an outbreak of mosquitoes the 
species involved can be determined quickly by collecting adults from 
various parts of the affected area. In localities where mosquitoes are 
present more or less continuously, or where outbreaks are of frequent 
recurrence, collections should be repeated often enough for the rela- 
tive annual abundance of the different species to be determined. At 
the same time information should be accumulated as to the breeding 
places of the common species, the topography of the area, and the 
extent of the control problem. A year should ordinarily be regarded 
as the minimum time for such preliminary studies, since mosquito 
abundance varies greatly with the seasons. Several years are re- 
quired to obtain rehable averages as to normal abundance. Although 
control operations usually can be begun before such an extensive 
survey is completed, the practice of beginning such work with in- 
adequate information is highly wasteful and may result in complete 
loss of public confidence in a worth-while project and possibly cause 
its abandonment. An important item in the annual budget for 
financing the control operations should be the provision for con- 
tinuing the systematic collection and identification of specimens. 
Such work will furnish invaluable information as to seasonal changes 
in the mosquito problem and outbreaks from overlooked or distant 
