IMPOUNDING WATER TO CONTROL BREEDING OF MOSQUITOES. 3 



proceeds from the banks of these streams to either side. The 

 deposits from these overjflows account for the ridges along the bayous 

 and the ancient channels of the river. There is, therefore, a gradual 

 fall from these ridges to the lands that lie on either side. These 

 lower lands are extensive swamp areas in the basins of which are 

 found permanent swamp " lakes " which are extremely shallow. The 

 banks of the bayous are formed with a steep declivity toward their 

 channels in contrast to the gradual slope toward the swamp areas 

 that lie parallel to them. The region is further characterized bj^ 

 narrow, crescent-shaped lakes within well-defined banks of the old 

 beds of the river, known as " ox-bows " or " cut-offs, " formed where 

 the action of the river has cut a new channel through the neck of 

 one of its many horseshoe bends. The ends of these " cut-off " lakes 

 are usually shallow, showing marshlike conditions, but the main 

 body of water is open and comparatively deep. The bayous are 

 not connected with these lakes except during periods of high water. 

 The swamp lakes tend to drain into the bayous at points lower down 

 in the courses of these streams. 



FAVORABLE CONDITIONS FOR MOSQUITO DEVELOPMENT. 



The swamp areas and the channels of the bayous are attended by 

 a rank growth of vegetation consequent upon the fertile nature of 

 the alluvial deposit and the prevalent moisture which, with the re- 

 sulting sediment and vegetable debris, promotes an ideal environ- 

 ment for the development of certain species of mosquitoes under 

 favorable climatic conditions. The situation becomes increasingly 

 emphasized by reason of the imperfect drainage due to the slight 

 fall of the land. Among the mosquitoes. Anopheles are found to 

 thrive, and the disease which they convey is prevalent among the 

 inhabitants of the region. 



LOCATION OF CULTIVATED LANDS, ROADWAYS, AND DWELLINGS. 



In the Delta the timbered lands are practically synonymous with 

 the swamp areas. The open lands, or lands under cultivation, are 

 confined to comparatively narrow strips along the ridges that form 

 the banks of the river, the bayous, and the old courses of these 

 streams. These lands are known as the " front " lands and from 

 the nature of their deposits are sandy in character. The lands lying 

 toward the swamp areas are known as the " back " lands and are a 

 heavy clay^ impervious to water, called " buckshot." 



The roadways of the region follow the higher lands and, wher- 

 ever practical, are carried along the bayou banks. The open land 

 is cultivated under the pegro tenant system, each tenant living upon 

 the land assigned to him for cultivation. It is therefore logical to 

 find the homes of the tenants on a roadway along the bayou where 



