BOLL WEEVIL CONTROL BY USE OF POISON. ile 
Mississippi. Here the plantations are fairly large, usually involv- 
ing at least 500 acres of cotton in a single organization and fre- 
quently a much larger area than this. Under such conditions the 
poisoning is conducted upon the heavily infested fields with a two- 
fold object: (1) To secure a reduction in weevil injury upon such 
fields, and (2) to reduce the numbers of weevils to the point where 
they will not migrate to the adjoining cotton. It has been found 
that by operating under such a system it is practically never neces- 
sary to poison the entire acreage. Complete economic control of 
the weevils for the entire acreage can be secured by concentrating 
or the most heavily infested cuts early in the season and thus pre- 
venting weevil multiplication and migration. This is particularly 
advantageous in that it distributes the cost of poisoning over a much 
wider area than would otherwise be the case. On the other hand, 
this system has the disadvantage, which will be discussed later, of 
requiring a rather complicated organization for conducting the 
‘poisoning work. 
In districts where the cleared areas are smaller, or farther South 
where the weevil mortality is so low during the winter that hiberna- 
tion is possible practically throughout the fields, a more generally 
distributed infestation is found early in the season and it becomes 
necessary to treat all fields alike. This is especially true in districts 
of small farms where the fields are comparatively small in extent and 
are more or less surrounded by weevil hibernation quarters. Under 
such conditions the only safe method of procedure is to poisen the 
entire area alike, and this naturally requires a larger amount of 
poison per acre than is the case where it is necessary to poison only 
a portion of the crop. 
TIME OF STARTING POISONING. 
Many studies have been conducted upon the subject of determining 
che proper time for starting poisoning, but so far no thoroughly sat- 
isfactory simple method has been devised. In order to secure uni- 
formity, in studies conducted during the past, a system cf what is 
termed “percentage of infestation ” has been utilized. This means 
the percentage of squares present in the field which are weevil-punc- 
tured.. While this is fairly simple of determination, a certain amount 
of care is required if false conclusions are to be avoided. The method 
utilized throughout this work has been to examine a hundred or 
more squares at several points in a field—usually the four corners and 
the center, although this is not generally necessary under ordinary 
farming conditions. The percentage of these squares which are 
weevil-punctured is noted and serves as a basis for the poisoning op- 
erations. In this connection, however, it should be noted that weevil 
