JOURNAL OF ECONOMIC ENTOMOLOGY 
196 
[Vol. 17 
classes, one dealing with regional losses in a series of years and the other 
with losses accruing in a single district in a single season. 
In determining regional losses the only method followed has been to 
compare the production per acre before and after the advent of the 
weevil. This is by no means a precise method. One reason is that 
there are frequently trends towards reduction in production due to the 
depletion of the soil and to other factors, which began to appear long 
before the coming of the weevil. It is frequently impossible to differ¬ 
entiate between the effect of these trends and what the weevil has done. 
Another difficulty is that production per acre in the country is not 
determined accurately except in the census years and intermediate years 
are only estimated. 
In determining the loss in any one season an effort has been made by 
entomologists to ascertain the amount by finding the percentage of 
infested squares and bolls throughout the season. This quantity can be 
obtained readily. With its use and a proper allowance for natural 
shedding a fairly accurate basis is secured. The practical difficult}" is 
to obtain sufficiently extensive series of field examinations. Up to 
recent times this has been the most accurate method available. Now, 
however, a different system can be followed and is being used to a con¬ 
siderable extent. This makes use of the fact that when properly applied 
calcium arsenate practically eliminates the factor of weevil damage in 
a field. The difference, therefore, between the production on treated 
plots and on check areas gives an accurate reading of the results of the 
work of the weevil. The degree of accuracy attained depends upon the 
proper selection of control areas (not always an easy matter) and the 
attacks of such insects as plant lice, which, however, generally affect 
controls and treated areas to about the same extent. The Bureau of 
Entomology has had numerous experimental plantings for several years 
in many states. They were located with reference to regional differences. 
The results obtained give by far the most accurate effort of estimating 
damage which has ever been devised. The precision and usefulness of 
this system could be greatly increased by the cooperation of the states 
in placing treated and check plots wherever needed. 
The method of estimating insect losses through the Crop Reporting 
Service is well known. Trained correspondents of several classes report 
their opinions as to the amount of weevil injury based on their own 
observations and information obtained from local farmers. The result 
is merely a crystallization of the conception of the farmers as to what 
the losses may have been. Its greatest weakness is in the natural 
