POISONING COTTON-BOLL WEEVILS. 15 
of a single application was as pronounced as 1s ordinarily secured 
from about three applications on a small plat, due, of course, to the 
constant migration of weevils into the small plat 
COST OF TREATMENT. 
The cost of treatment will, of course, vary widely. In the-strictly 
experimental tests conducted so far it has averaged usually about $1 
an acre for each application. It must be recognized, however, that 
it will be possible to reduce this considerably when applications are 
made on a larger scale, and, with improved machinery, a further 
reduction will result from the lessened poison requirements. In 
addition, the probability that it will be possible to utilize carriers and 
thus further reduce the amount of poison required per acre renders the 
cost subject to a still greater reduction. It should be remembered, 
also, that very rarely will it be necessary to poison an entire planta- 
tion to control the weevil infestation. The weevils on emerging in 
the spring will always concentrate near the hibernation quarters in 
which they spent the preceding winter. They remain rather closely 
at these points until they have multiplied sufficiently to threaten a 
shortage in the local food supply. For this reason a great part of the 
cotton is not seriously infested with weevils until some time after 
midseason and often not until well along in August. Of course the 
control measures adopted must depend on conditions on each plan- 
tation, but by concentrating on the more heavily infested cuts just 
before the weevils become sufficiently abundant to start movement 
to the remainder of the cotton it will be possible not only directly to 
benefit the cotton treated, but to protect the remainder of the plan- 
tation by preventing the weevil migration. In this way the cost of 
the treatment for a comparatively few acres will be borne by the 
benefit derived by the entire plantation. In this connection, it prob- 
ably will often prove advisable to give several applications to the 
more heavily infested cuts and perhaps only a single application to 
the remainder. 
NECESSITY FOR FURTHER EXPERIMENTAL WORK. 
In conclusion it should be emphasized that the present bulletin is 
merely a ‘‘progress report”? and the writer does not wish to be con- 
strued as in any way advising the general use of these poisons for 
boll-weevil control. There are now too many doubtful points, 
especially as regards the technique of application; and, as has been 
shown, the technique of application largely determines the benefits 
derived. At the present stage of the investigation it is impossible to 
outline a definite plan of procedure for the poisoning of weevils under 
all conditions, and much more experimental work will be required 
before such a plan can be proposed. With the present lack of infor- 
mation on so many important points, any attempt to poison the 
weevil by the inexperienced may very easily result in actual loss. 
