16 BULLETIN 358^ U. S. DEPARTMENT OF AGRICULTURE. 



From the results of these two series, shown in Tables VI and VII, 

 it develops that p^U of the 25 isolated females deposited eggs, although 

 4 of them deposited less than 10 eggs each, whereas of the 20 fertilized 

 females only 3 individuals deposited less than 10 eggs. The average 

 oviposition period was 34.5 days for the isolated females and 40 

 days for females with the males. The average eggs for the isolated 

 females was 41.2 with a maximum of 129, while for the females with 

 males the average was 69.8 with a maximum of 157. However, it 

 is seen that the isolated females averaged 5 eggs deposited externally 

 whUe the females with males averaged only 0.45. Earlier studies 

 have shown that practically all eggs deposited externally are infertile, 

 which would indicate a lack of fertility on the part of isolated females. 

 The average eggs per day for the isolated females ra.nged from 0.1 

 to 3.1 with a general average of 1.03, whereas for the females with 

 males it ranged from 0.6 to 5.6 with an average of 2.05 eggs, thus 

 proving the greater fecundity of the females with males. 



The latest date of cessation of oviposition, August 23, was the 

 same in both series, but the average date for the isolated females 

 was 7 days later than that of the females with males. All eggs secured 

 in both series were retained and as many adults as possible were 

 reared. It is seen that 17.25 per cent of the eggs from the isolated 

 females produced adults, while 14.46 per cent of those from the 

 females with males produced adults. However, the eggs from every 

 female in the series with males produced some adults, while those 

 from 4 females in the isolated series failed to produce any. 



From these observations it seems quite evident that at least a 

 very high percentage of the females emerging in the spring are more 

 or less fertile, but that their fecundity is considerably increased by 

 later copulations. 



Fecundity of first-generation grandis females. — The weevils used in 

 this series were the first weevils bred during the season of 1915, the 

 earliest emerging June 20. Thirteen jjairs were mated and placed 

 with cotton squares. (Table VIII.) 



