﻿14 



BULLETIN im, IT. S. DEPARTMENT OF AGEICULTUEE 



the rest. Dorsal area of each armed with a pair of large spines and a pair of 

 smaller ones. Lateral area of each tergite bearing a spine, at base of which is 

 a small seta. Epipleural lobes each obscurely armed with two minute set«. 

 Ninth segment armed as usual with two prominent pleural spines. 



LIFE HISTORY AND HABITS 



The granary weevil normally hibernates during the winter in 

 either the adult or the larval form. The adult is resistant to low 

 teniperatures and will survive a very cold winter. Adults resume 

 activity with the first warm weather of spring, and egg laying soon 

 begins. Overwintering larvae at that time begin pupating. Hiber- 

 nating adults kept in the laboratory at Washington, D. C, resumed 

 egg laying in the early part of March. 



THE ADULT 



After transformation from the pupal 

 to the adult form, the weevil remains 

 within the seed for a short time until 

 the body integuments harden and the 

 color has changed to a dark chestnut 

 brown. Some weevils remain to feed 

 for a considerable time within the 

 larger seeds. Shortly after emergence 

 copulation takes place and is repeated 

 at frequent intervals throughout the 

 life of the weevil. 



The weevils are rather sluggish in 

 their actions and are very easily 

 handled. If disturbed in any way 

 they draw their legs up close to the 

 body and remain motionless for some 

 time. The females may be distin- 

 guished from the males by their 

 smoother and more slender beaks. 



PARTHENOGENESIS 



„ ^ o „, ., ^ , , Virgin females of the granary weevil 



Fig. 8. — The granary weevil: Pupa, ventral , 9 , i , 1 • r 



view. Enlarged about 37 times have been oDserved to dcposit an oc- 



casional egg, but none of these hatched. 



DURATION OF ADULT LIFE WITHOUT FOOD 



The granary weevil is capable of surviving without food for a 

 considerable period, much longer than the closely related rice weevil, 

 possibly because of its less active life and its restriction to a more 

 temperate climate. The temperatures at which the insects were kept 

 under observation had a very marked effect on their powers of resist- 

 ance to starvation. Five lots of 50 weevils each were kept without 

 food until they died. Each lot was placed in a separate compart- 

 ment held at a constant temperature. These temperatures ranged 

 from 55° to 85° F. and were maintained with but slight variation 

 for the entire period and at a rather high humidity. The results are 

 given in Table 1. 



