﻿30 BULLETIN 13&3, IT. S^ DEPAETMENT OE AGEICtlLTUIlE, 



The nuining of grain from bin to bin during very cold weather has 

 been practiced. The writers observed this method of reducing the 

 temperature of grain during the war period when wheat, in being 

 transferred, was allowed to fall through the air during zero weather 

 from a height of about 25 feet. If grain can be sufficiently chilled 

 by rimning, it can be protected from weevil attack. Even if its tem- 

 perature can not be lowered to the point where the cold will prove 

 fatal to the insect's hfe, much good will result from the suspension 

 of its activity. 



Since the control of the granary weevil is not different from that 

 of grain pests in general, no further discussion of control measures is 

 given. 



SUMMARY 



The granary weevil, SitopMlus granarius L., has been known as a 

 grain pest from ancient times. Recognized as a distinct species by 

 Linne in 1758, it has since been discussed as a pest of economic im- 

 portance by many writers but has not been studied seriously, from 

 a biologic standpoint, until within the last few years. It is often 

 confused with, though easily distinguished from, the closely related 

 and more destructive rice weevil, SitopMlus oryza L. 



The granary weevil is considered to have originated in either Asia 

 or the Mediterranean region. Unlike other menibers of the genus 

 Sitophilus, however, which thrive best in tropical and semitropical 

 climates, the granary weevil is now distinctly a temperate-climate 

 species with a world-wide distribution. In the United States it ap- 

 pears to be giving way to Sitophilus oryza, and to be the prevailing 

 calandrid species only in the more northern States. 



Provided with no effective wings and by nature not very active, 

 the granary weevil is found primarily in the granary or storehouse 

 and depends upon man for dissemination. It does not appear to be 

 well equipped to meet present-day methods of handling and pro- 

 tecting grain, with the result that, in the United States at least, it 

 seems to be losing some of its importance as a pest in grain and 

 certain grain products. 



Like calandrid pests in general, the granary weevil causes the de- 

 struction of grain and grain products by the direct feeding of the 

 adult beetle and its larva. Adult beetles, being long-lived and vora- 

 cious, devour much grain throughout their life. They feed not only 

 upon whole grains but upon stock feeds containing cracked grain 

 and even upon finely divided products such as flours. The larvae 

 feed upon whole grains or upon portions of grains sufficiently large 

 to support the larva throughout its entire development. Although 

 larvae will not develop in finely divided cereal products such as flours 

 and meals, they can probably develop in these when they become 

 caked from one cause or another. The adult weevils occasionally 

 are destructive by boring holes in the cartons of packaged cereals. 



The granary weevil hibernates during the winter months as adult 

 or larva. With the approach of warm spring weather, the adults 

 begin to oviposit and the larvae to feed and transform. Newly ma- 

 tured adults may remain in the seeds for some time before they 

 emerge. Shortly after emergence copulation takes place and is re- 

 peated at frequent intervals throughout life. Parthenogenetic eggs 

 may be laid occasionally, but do not hatch. 



