70 Proceedings of Ninth Annuai, Meeting 



before the work was done and with the changed conditions 

 brought about by the work. Special reference is made to the 

 breeding of mosquitoes, and there is a discussion of the impound- 

 ing of water in a bayou from the standpoint of plantation econ- 

 omy. 



The bayous, or streams, of the delta region of the lower Mis- 

 sissippi valley are characteristic of those found in all delta accum- 

 ulations. The bayous flow away from the main stream, the 

 Mississippi river, and there is a gradual slope from their banks 

 to the swamp lands that lie on either side. The bayous are not 

 connected with the lakes peculiar to the region except at seasons 

 of high water. There is a slight fall in the beds of these streams. 

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

 a rank growth of vegetation, consequent upon the fertile nature 

 of the soil and the prevalent moisture which, with the resulting 

 sediment and vegetable debris, promotes an ideal environment for 

 the development of certain species of mosquitoes. The situation 

 becomes increasingly emphasized by reason of the imperfect 

 drainage. Among the mosquitoes Anopheles are found to thrive, 

 and the disease which they convey is prevalent among the inhabi- 

 tants of the region. 



The roadways of the delta country follow the bayou banks 

 wherever it is practical, as the ridges along these streams are 

 higher than the surrounding lands. The land is cultivated under 

 the negro 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 one of these 

 streams bounds or sections a property. The houses thus located 

 are in the higher and more open portions of the plantation, and 

 usually maximum distance from the swamp areas on either side. 

 It is evident that such location of the habitations is favorable in 

 respect to distance from the breeding areas of Anopheles mosqui- 

 toes, with the exception of the mosquitoes that originate in the 

 bayou itself. 



Of course, complete drainage is the logical method for the 

 disposal of surface water in Anopheles control, where that method 

 applies, but in the absence of a drainage outlet, and in the pres- 

 ence of surface water, favorable for breeding throughout the 

 season, other means must be given local consideration. In any 

 consideration of drainage in the delta it is necessary to note that 

 the bayous flow away from the river, that the slope of the land is 

 from the bayou banks towards the swamp areas on either side, 

 and that the fall in the bed of the bayou averages less than one 

 foot to the mile. 



