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JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 4 



to the fact that they were reared at the time when the larval food was 

 insufficient, on account of the long period required for development 

 and the poor condition of the squares suppUed. They do not, therefore, 

 probably represent the normal time required by weevils at that season, 

 but exceed this time by several days. The average time of 7.72 days 

 is also probably somewhat in excess of the normal average. 



The number of eggs produced on the first day of oviposition shows 

 remarkable variation, from one to seven. Of the forty-three weevils, 

 sixteen produced one egg and thirteen two eggs; in other words more 

 than 67 per cent of the weevils deposited, on the first day of oviposition, 

 less than three eggs. Some of the others responded more readily to 

 the incentive furnished by the abundance of squares and probably 

 exceeded their normal habit. 



A summary, by groups, of the results of these observations are shown 

 in Table IV. 



Developmental Period 



Incubation period. — Data on the incubation period were obtained 

 from six lots of eggs. Of these, four lots, deposited June 27 to July 

 4, showed a period of about three days, and two lots, deposited July 

 8-10, gave a period of about two and a half days. A study of the aver- 

 age temperatures during the incubation periods of these six lots of 

 eggs shows that the average maximums for the eggs having the short- 

 est incubation periods were much higher than for those requiring the 

 longer period, the means slightly higher, and the minimum slightly 

 lower. This indicates that the maximum temperature is the deter- 

 mining factor in the duration of the incubation period. This is shown 

 very clearly in Table V. 



TABLE V 



TABLE SHOWING RELATION BETWEEN INCUBATION PERIOD OF ROLL WEEVIL AND TEMPERATCRB 



