Chapter IT. 
THE MALARIA MOSQUITOES. 
The Culicidae, or mosquitoes, belong to the true hies, or Diptera, 
and the only insects of this family of interest to us in thp prophylaxis 
of malaria are some of the species belonging to the subfamily Anoph- 
elinw , for it is only species belonging to this subfamily that transmit 
malaria. In this section only those points of interest or value to the 
student of malaria prophylaxis will be touched upon, no attempt be¬ 
ing made to give a complete account of either the anatomy or life 
history of the mosquitoes, as a whole, or to give descriptions of the 
species concerned in the transmission of the malarial infections. For 
a complete discussion of the subject the reader is referred to works 
of Theobald ', Howard, Dyar, and Knabe (i , and Ludlow 7 . 
(ideographical distribution of the Anophelinw .—-Mosquitoes belong¬ 
ing to the Anophelinai occur wherever malaria does, but it does not 
follow that malaria is always present in localities where the Anophe¬ 
linai are found. In order that malarial infections be present in any 
locality, the right species of Anophelinw must be present, together 
with infected individuals, and unless both factors be present the 
propagation of these fevers is impossible. It may be stated that the 
geographical distribution of the malaria mosquitoes coincides with 
the distribution of malaria, and the amount of malaria in any given 
locality is an index of the number of the Anophelince present. 
This fact is of great importance in the prophylaxis of the disease, 
as the determination of the presence of anophelines and of the exact 
species present enables one to avoid localities inhabited by the mala¬ 
ria mosquitoes or to take the proper precautions against infection. 
Such knowledge is of special value in the military service, as a pre¬ 
liminary “ mosquito survey ” in the selection of localities for camp 
sites or for the sites of military posts will often prove of inestimable 
value, both as regards the health of the troops which occupy them 
and the cost of maintenance. Several instances have occurred in 
which this measure was neglected, with the result that the camps or 
posts so located became hotbeds of malaria and a source of continued 
and excessive expense, owing to the necessity of maintaining costly 
prophylactic operations. Where there is no military reason for occu¬ 
pying a malarial locality as a camp site, or as a permanent post, it is 
the part of wisdom to avoid doing so, and the determination of the 
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