4 BULLETIN 1098, U. S. DEPARTMENT OF AGRICULTURE. 
one of these streams bounds or sections a property... The houses 
thus located are in the higher and more open portions of the plan- 
tation and usually at maximum distance from the timbered and 
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 mosquitoes, with the exception of those mosqui- 
toes that originate in the bayou itself. 
PROBLEM OF ANOPHELES CONTROL IN THE REGION. 
Of course complete drainage of surface water is the logical method 
of Anopheles control where that method applies, but in the absence 
of a drainage outlet, and in the presence of surface water favor- 
able for Anopheles breeding throughout the season, other means 
must be given local consideration. In any consideration of drain- 
age in the Delta it is necessary to note that the streams of this 
region flow away from the river, that the slope of the land is 
from the bayou bank toward the swamp areas on either side, and 
that the fall in the bed of the bayou averages less than a foot to the 
mile. Under these conditions the question of drainage involves an 
extensive area; it is not a matter which the plantation owners can 
consider individually. 
The idea of impounding water to suppress mosquito breeding is 
rather foreign to the general conception of the effect of impounded 
water upon mosquito production. The relation which impounded 
water will bear to mosquito production depends altogether upon the 
conditions under which the work is done and the changes brought 
about in comparison to the natural conditions. In the question of 
impounding water in a bayou we must consider the natural character 
of such a stream and the relation of the stream to the roadways of the 
plantation and the habitations of the people who cultivate the land. 
The bayou bank is the logical location for the houses of the tenants 
and it is important to control the breeding of Anopheles in this near- 
by source. The bayou under natural conditions favors mosquito pro- 
duction but under impounded conditions does not. The change in 
conditions is brought about by the preliminary clearing and by the 
provision for a permanent water level sufficiently high to suppress 
the growth of aquatic vegetation. Following these operations, the 
maintenance of a clean margin is all important. 
BAYOU WALNUT AND THE ANOPHELES SURVEY. 
The work of the Bureau of Entomology was done in a section of 
Bayou Walnut which quarters the southwest portion of Hecla plan- 
tation. This bayou runs a very irregular course from a point slightly 
north of Milikens Bend on the Mississippi River to Bayou Round- 
away, joing the latter stream southwest of Tallulah, From the 
