6 BULLETIN 10&8, U. S. DEPARTMENT OF AGRICULTUEE. 



hand, breeding was found in those portions of the bayou where the 

 margins were grass-grown or supported a growth of overhanging 

 trees and vines ; where the water surface was covered with the result- 

 ing vegetable debris or floatage ; where the water was shallow enough 

 to support the growth of aquatic vegetation in the bed of the stream ; 

 where the channel was blocked by trees, logs, stumps, and brush ; or 

 where the bed was partially dry, permitting the summer rains to 

 maintain isolated pools in natural depressions, in hoofprints of ani- 

 mals, and in mud cracks. A comparison of these conditions in the 

 natural bayou is shown in Plates I and II and Plate III, Figures 1 

 and 2. 



The collections of Anopheles larvae in the general survey work 

 during the years 1914 and 1915 gave, for Bayou Walnut within the 

 limits of Hecla plantation, the records which are shown in Table 1. 



