UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1393 
Washington, D. C. 
May, 1926 
THE GRANARY WEEVIL 1 
By E. A. Back, Entomologist in Charge, and R. T. Cotton, Associate Entomolo- 
gist, Stored- Product Insect Investigations, Bureau of Entomology 
CONTENTS 
Introduction 
Synonymy 
Economic history 
Origin and distribution- 
Nature of injury 
Technical description.. . 
Page Page 
._ 1 Life history and habits 14 
.. 1 Parasites 29 
.. 3 Control measures 29 
. 5 Summary 30 
.. 7 Literature cited 32 
INTRODUCTION 
The granary weevil (Sitophilus granarius L.) (fig. 1) is well named, 
for of all the primary grain pests it is par excellence a pest in the 
granary or storehouse. Unlike its more successful and widespread 
rival, the rice weevil (Sitophilus oryza L.), the granary weevil pos- 
sesses only rudimentary wings and does not appear to thrive in 
tropical and semitropical climates. Restricted as it is to the gran- 
aries of the colder climates, it seems to be finding it increasingly 
difficult to withstand the combined effect of limited numbers of 
generations due to cold and the modern methods of handling and 
protecting grain. 
As late as the decade from 1860 to 1870 the granary weevil was 
the prevailing species of weevil in grain throughout the northern 
portion of the United States. E. A. Schwarz, of the Bureau of 
Entomology, states that Sitophilus granarius was the only grain 
weevil present among the insects collected by C. V. Riley in Missouri 
and later acquired by the United States National Museum. The 
writers, who have examined many samples of grain from various 
grain centers of this country, believe that the granary weevil is a 
minor pest as compared with the rice weevil, and that it is responsible 
for a relatively small amount of the damage caused by calandrid 
pests in this country, notwithstanding the numerous instances of 
serious injury that are constantly coming to one's attention. Keys 
distinguishing the larvae and adults of granarius and oryza have 
been given by Cotton (13). 2 
SYNONYMY 
The granary weevil was described and named by Linne (44> V- 3?S) 
in 1758 as Curculio granarius. Numerous references to this weevil 
1 The biological data contained in this bulletin are based on work conducted in Florida from 1919 to 
1921 and in Washington, D. C, from 1921 to 1923. 
3 Reference is made by number (italic) to "Literature cited," p. 32. 
72238°— 26 1 
