6 BULLETIN 1098, U. S. DEPARTMENT OF AGRICULTURE. 
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 débris 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 ITI, Figures 1 
and 2. 
The collections of Anopheles larve 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. 
