The Bulletin". 



51 



General Life-history of Grain Weevils. — As there are a number of dis- 

 tinct kinds of grain weevils, some seeming to prefer ground grain prod- 

 ucts, the life-histories vary in details. The account here given is only 

 meant to be general, giving an approximate idea of the whole group. 



Pig. 18. — Grain Weevils (beetles), showing two 

 closely related species at a and d ; a larva at 

 h. and pupa at c. Natural size indicated by 

 lines. The one at d is the "Black Weevil," 

 our most destructive corn weevil. 



(After Chittenden. Div. Ent., U. S. 

 Dept. Agr.j 



The adult insects are moths or beetles, mostly small, but a few of 

 medium size. These lay eggs on or in the grain or husk and the worms 

 eat into the kernels. In some species the worm reaches full growth in 

 the same kernel in which it first hatches ; in others the same worm may 

 live in several different kernels. When grown, the worm changes to a 

 pupa from which the adult moth or beetle emerges later. In the case 

 of weevils infesting meal, bran, and other ground materials, the worms 

 burrow around in the material, frequently spinning a web which fastens 

 little masses together. Meal and other products thus infested are apt 

 to become moldy and unhealthy as food for both man and beast. Where 

 the whole grain is infested, the vital germ is often eaten out, thus spoil- 

 ing the grain for seeding purposes. 



In the previous Bulletin of this Department on "Corn Insects" the 

 writer stated that adult weevils had been found "passing the winter in 

 the remnants of fodder where this had been pulled," but he has not now 

 the original note at hand. His recollection is that it was the "Black 

 Weevil," found in winter in the husk remaining attached to the stalk. 



