26 



Usinger: Introduction 



■ .: 



m^i 



Intro, fig. 32. Sleeve sompler used for shallow water mosquito 

 breeding places in irrigated pastures (Yamaguchi, 1949). Larvae 

 are sucked out of the plastic cylinder by the "pump" and then 

 ejected into the enamel pan for counting. 



Intro, fig. 34. Use of dynamite for construction of a drainage 

 ditch for mosquito control (U.S.P.H.S., C.D.C. photo). 



Intro, fig. 33. Drainage is the most permanent and therefore 

 one of the most effective methods of mosquito control (U.S. P. 

 H.S., C.D.C. photo). 



able to incubate the malaria parasites and transmit 

 the disease. Other measures directed at adult mos- 

 quitoes include screening, nets of various kinds, 

 and repellents such as "612," dimethylphthalate" 

 and the like. 



Most methods of mosquito control are directed 

 against the immature forms — the larvae and pupae. 

 One of the most important of all methods because it 

 is relatively permanent is the elimination of breeding 

 places by drainage (intro. fig. 33). Drainage ditches, 

 may be blasted (intro. fig. 34) or dug by dragline 

 (intro. fig. 35) or by hand labor. The cost of mainte- 

 nance may be greatly reduced if drainage ditches are banks (intro. fig. 36a, before concrete lining; 6, after), 

 lined with concrete and sod planted on the upper Underground drainage is commonly used in seepage 



Intro, fig. 35. Dragline ditching at Marysville, California 

 (U.S. Army Signal Corps). 



