﻿THE GEANAEY "WEEVIL 15 



Table 1.- — Resistance of the granary weevil to starvation 



Date 



Num- 

 ber of 

 days 

 starved 



Number of adult weevils 

 found dead at— 



Date 



Num- 

 ber of 

 days 

 starved 



Number of adult weevils 

 found dead at— 





55° F. 



60° F. 



68° F. 



76° F. 



85° F. 



55° F. 



60° F. 



68° F. 



76° F. 



85° F. 



1920 

 June 24_.. 



7 

 8 

 9 

 10 

 11 

 12 

 14 

 15 

 16 

 17 

 19 

 20 

 21 

 22 

 23 





 5 

 

 

 

 7 

 3 

 

 

 5 

 3 

 2 

 4 

 6 

 5 





 

 

 

 4 

 7 

 

 5 

 3 

 2 

 

 

 

 3 

 





 11 

 5 

 

 

 

 7 

 

 

 4 

 

 0- 

 5 

 

 6 



12 

 12 

 4 

 2 

 14 

 3 

 2 

 

 1 



28 

 

 4 

 

 

 7 

 2 

 

 7 

 1 

 1 



1920 

 July 12... 



14... 



15... 



16... 



17... 



18... 



19... 



20... 



21... 



23... 



29... 

 Aug. 3... 



10... 



21... 



25 

 27 

 28 

 29 

 30 

 31 

 32 

 33 

 34 

 36 

 42 

 47 

 54 

 65 





 

 

 3 

 

 2 

 

 

 1 

 

 1 

 1 

 1 

 1 



7 

 6 

 2 

 

 7 

 

 

 3 

 

 1 





 3 

 

 4 

 

 

 3 

 

 2 







25... 







26.__ 







27... 







28... 







29... 







July 1. 







2... 







3... 







4... 







6_.. 









7... 











8... 















9... 















10... 























The weevils subjected to a temperature of 85° F. were very active; 

 more than 50 per cent died at the end of the first week of starvation, 

 a few hngered on for some days, and one survived for 19 days. The 

 weevils kept at 55° F, were sluggish; 50 per cent survived for three 

 weeks and one for 65 days. 



DURATION OF ADULT LIFE WITH FOOD 



The average length of life with food, as indicated, by the data in 

 Table 2, is between 7 and 8 months. 



This is the average of 35 females observed for oviposition records. 

 Several individuals not included in this table lived, considerably 

 longer. Of a number of weevils that emerged on May 1, 1921, one 

 female lived imtil July 2, 1922, and two females until July 10, 1922, 

 a period of a little more than 14 months. The effect of a moderately 

 low temperature, which permits occasional feeding but at which the 

 adults are decidedly sluggish, is greatly to prolong life. Thus, of 30 

 adults placed, on September 18, 1921, in a refrigerator of the ordinary 

 type, which maintained a temperature between 50° and 60° F., one 

 hved two years and five months and four were still alive on January 15, 

 1924. Although adult life may l)e prolonged to cover a two-year 

 period, it is not likely that conditions favoring such a long life obtain 

 under normal warehouse conditions. The average length of life, as 

 stated above, is about seven or eigiit months, with certain individuals 

 living well over one year, 



PUEOVIPOSITION PERIOD 



The data of Table 2 indicate lliat the granary weevil begins ovi- 

 positing from 6 to 148 days al'lcr emergence. In early spring females 

 negin ov^if)ositing about tliree weeks after emergences. Later, in 

 the summer, the preovifjosilion period is reduced to aj)proximately 

 one w(!ck. Weevils emerging Inle in i\\(\ full have Uk? longest |)reovi- 

 position [)erio(l, since they usually do nc^t begin to oviposit until the 

 following spring. 



