File:Airplane dusting in the control of malaria mosquitoes (1926) (17760112258).jpg

Title: Airplane dusting in the control of malaria mosquitoes
Identifier: airplanedustingi367king (find matches)
Year: 1926 (1920s)
Authors: King, W. V. (Willard Van Orsdel), b. 1888-; Bradley, G. H. (George Hirst), b. 1893-
Subjects: Mosquitoes Control
Publisher: Washington, D. C. : U. S. Dept. of Agriculture
Contributing Library: U.S. Department of Agriculture, National Agricultural Library
Digitizing Sponsor: U.S. Department of Agriculture, National Agricultural Library

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(3 Department Circular 367, U. S. Dept. of Agriculture work is required in making preliminary examinations and in check- ing the results. A full description of the shallow swamp lakes found in this region has been published recently by one of the writers4 and will not be repeated in detail here. In general, they are the principal sources of Anopheles mosquitoes and as a rule consist of a central treeless area of more or less permanent water, surrounded by a dense mar- ginal growth of trees and brush. (Fig. 3.) The central area is usu- ally overgrown with water chinquapin and water lilies (Xelumbo and Castalia) and other smaller aquatic vegetation. In winter the lakes become filled and the water spreads out into the woods, often covering large areas and producing favorable conditions for mos- quito breeding in spring and early summer. As the excess water drains away or evaporates, the larvae are found in the more open
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Fig. 3.—One of the larger swamp lakes parts of the lakes away from the trees. The principal difficulty anticipated in treating such areas was in reaching the larvse in the wooded marginal zones. In the first of the three lakes selected, known as Field Lake, the open part was something over a half mile in length and perhaps one.- fourth as wide as long. Between the lake and a cleared pasture on one side was a narrow fringe of flooded woods varying in width from 50 to 200 feet. Breeding was prolific in this fringe and in places in the open lake, under the thick growth of lilies and in mats of mud plantain and Ceratophyllum. In preparing for the dusting flights larval examinations were made at 10 or more points in the part of the lake to be treated, and a glass plate was left on a floating block at each of these " stations." From the plates it was possible to * G. H. Bradley. The natural breeding places of Anopheles mosquitoes in the vicinity of Mound, La„ In. Amer. Jour. Trop Med., vol. 4, pp. 199-223, 1924.

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