CIRCULAR No. 100. Issued November 2, 1911. 
United States Department of Agriculture, 
BUREAU OF ENTOMOLOGY. 
L. O. HOWARD, Entomologist and Chief of Bureau. 
AN INDEX TO CIRCULARS 1 TO 100 OF THE BUREAU 
OF ENTOMOLOGY. 
By Rotxia P. Currie and ANDREW N. CAUDELL. 
The first circular of the present series, or what was formerly 
known as the second series, of the Bureau of Entomology was issued 
in 1891, while Circular 99 was issued in 1908. The circulars of the 
first series, something over 40 in number, were nearly all merely cir- 
cular letters and had only a temporary value. Very few of these first- 
series circulars are now known to exist, and even the titles of most of 
them are now unknown. 
While some of the circulars of the present, or second, series were 
in the nature of emergency circulars, and were therefore soon discon- 
tinued or superseded, yet very many others were popular summaries, 
containing in condensed form all the important data available con- 
cerning the particular insects discussed. They have therefore a dis- 
tinct value to the student and worker in economic entomology as well 
as to the farmer, forester, horticulturist, and general reader. Many 
of the insects treated have not yet been made the subjects of bulletins 
or been considered in other publications of the department, and much 
information contained in these circulars is therefore not to be found 
elsewhere. 
To make this information more easily available and to prevent it 
from being overlooked, the present index has been prepared, and it is 
hoped that it will be of use to all who read or consult the circulars 
of the bureau. 
For convenience the index itself is preceded by a list of circulars 
1 to 100, with their revisions. This list may be considered as complete 
and final, since the policy of issuing revised editions of circulars, i. e., 
under the original serial number, has been discontinued and no more 
such will be published. 
Where circulars have gone through one or more revised editions the 
latest edition is the one indexed. 
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