﻿THE GEANAEY WEEVIL= 31 



It has been found that of adults held at 85° F. under starvation 

 conditions 50 per cent may die by the end of the first week, with a 

 certain few surviving for 19 days. Others, kept at 55° F., were 

 very sluggish; 50 per cent survived for about 3 weeks, and one for 

 65 days. When given food, adult life is much longer and averaged 

 between 7 and 8 months. Numerous adults lived well over 1 year 

 and of certain adults subjected to a temperature ranging between 

 50° and 60° F., a few lived for 2 years and 5 months. 



Adults begin ovipositing during summer as early as six days after 

 emergence. In early spring the preoviposition period is about three 

 weeks. Adults that emerge late in the fall have the longest preovi- 

 position period, since they hibernate and do not begin ovipositing 

 until the following spring. The extremes found in the preoviposition 

 period were 6 and 148 days. 



The granary weevil lays from one to five eggs per day when ovi- 

 position occurs, although one or two eggs per day is the more usual 

 number. There is, however, considerable variation, as between dif- 

 ferent females, in the number of eggs laid per day under identical 

 temperature conditions. This same variation extends to the dura- 

 tion of oviposition and to the total number of eggs laid by females. 

 The longest oviposition period recorded was 287 days, from August 

 27 to June 10 of the year following. The shortest oviposition period 

 was 67 days, from March 19 to May 25. The average length of the 

 oviposition period for adults emerging during spring and early sum- 

 mer is between three and four months. The total egg-laying ca- 

 pacity of single females varied from 36 to 254. 



The incubation period varied in length from 4 days at a mean 

 temperature of 78° to 80° F. to 15 days at a mean of 61° F. No 

 eggs were observed to hatch after the temperature of the grain had 

 reached 95° F. or above, or when it hacf fallen to 50° to 55° F. 

 Since adults do not oviposit until the temperature is from 61° to 

 63° F., and do not oviposit with ref^ularity until a temperature of 

 66° to 68° F. is reached, there seems little reason to believe that eggs 

 are ever laid when they can not hatch within 15 days, unless it be 

 in late fall on approach of cold weather, when they will fail to hatch 

 and will die. 



The larva must have for food seeds m size suflicicnt to supply 

 its growth requirements. In its growth it molts three times at more 

 or less regular intervals. Where development proceeded fairly rapidly 

 the duration of the four larval iiistars was found to be as follows 

 when the mean temperature varied from 59° to 84° F. : First instar, 

 4 to 12 days; second instar, 4 to 14 days; third instar, 4 to 17 days; 

 fourth instar, 6 to 24 days. Witli a good supply of normal moisture 

 content the larvye completed tlioir devcilopmoiit in from 19 to 34 days 

 during summer wc^ather wlien the mean temm^raturc ranged from a 

 maximum of 93° F. to a mininmim of 70° F. The longest larval 

 dcv(!lopment recorded by the wrifcrs is 59 days wlien the mean tem- 

 peratures vari(ul betwruin 77° and 49° F. 



After attaining its growth the larva prepanw a jnipal cell, and 

 after from on(! to two days in llic prepnpnl form it transforms to 

 the pupa. During the hottest snmmer weather, when i\u\ mean tem- 

 peratures vary from a maximum of 85° to 95° F. to a minimum of 

 61° to 71° v., the pu|)al stage lusts from 5 to 7 days (mean tem- 

 peratures for the p<!riod varying from 6S° to 82° F.). During (bolder 

 weather, with a mean temperal-ure for the period of developmcMit 



