10 BULLETIN 875, U. S. DEPARTMENT OF AGRICULTURE. 
ture stages developing in the bolls and squares. ‘These immature 
stages continue developing every day for a considerable period after 
the apphcation is made. A single application may tremendously re- 
duce the adult weevils present in the field at that time, but they will 
be replaced very quickly by the new generation which is maturing 
and emerging. Unless the applications are repeated at the proper 
time intervals, therefore, freshly emerged weevils will soon become 
sufficiently abundant to counteract all the benefit which may have 
been secured from the first treatment. In some cases one or two ap- 
plications may control the weevils sufficiently to permit the forma- 
tion of a considerable crop of young bolls, but unless these bolls are 
protected by continued applications the weevils usually will multiply 
with sufficient rapidity not only to infest the squares present but also 
to prevent these young bolls from reaching maturity. 
SEASON FOR APPLICATIONS. 
When it was first found possible to kill at least a certain percent- 
age of the weevils by poisoning, it seemed that the best results would 
be secured by early season applications, thus deriving the double 
benefit of killing the weevils then present and preventing the de- 
velopment of their potential progeny. Consequently the first tests 
were almost entirely early season applications. But it wassoon found 
that far more profitable results were secured by treatments later in 
the season. Thorough studies on this point have since shown quite 
definitely that by far the greatest profit is derived by making the 
applications at the critical time when the weevil injury is just begin- 
ning to exceed the normal shed of the cotton plants. Another im- 
portant point is that the plant is fruiting so rapidly at this time that 
every day of retardation of weevil infestation means a great deal in 
additional cotton production. 
The time when poiscning should begin has almost no relation to 
the size of the cotton plant and is purely a question of weevil 
abundance. Such factors, however, as the size of the farm or field 
involved will determine very largely the basis upon which poisoning 
can be planned. For example, in some districts where the culti- 
vated areas are large and more or less consolidated, weevil injury 
is very evenly distributed, owing to the fact that the weevil adults 
emerging from hibernation in the spring usually concentrate on the 
first fields they reach and do not seriously infest the more distant 
fields until they have practically overtaken the fruiting of this 
near-by cotton. This condition is found in many portions of the 
cotton belt and is particularly pronounced in the district where the 
majority of this Department’s tests have been conducted in the past, 
namely, the Mississippi Delta region of Louisiana, Arkansas, and 
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