14 



BULLETIN 231, IT. S. DEPARTMENT OF AGRICULTURE. 



DURATION OF FERTILITY AND FECUNDITY. 



Many experiments were conducted to test the duration of fertility 

 and the fecundity of the various types of weevils. With A. grandis 

 special experiments on this question were conducted in addition to 

 the regular breeding series. Kather thorough data were obtained on 

 the variety thurberise and the various crosses iu the different breeding 

 series of these. 



Fecundity of females of A. grandis in copula only once. — The previous 

 results on the exact duration of the fertility of females after copula- 

 tion were very indefinite and there were no records of the fecundity 

 resulting from only one copulation. In the course of the past sum- 

 mer's investigations the writer was able to secure considerable infor- 

 mation on this point. 



Eleven females were separated from the males immediately after 

 emergence and only returned to them about 6 hours each day when 

 under close observation. In this manner the first copulation of each 

 female was determined and she was then placed alone on squares to 

 test her fecundity with no more chances for fertilization. Of the 

 11 females so treated, five were fertile, four were infertile but deposited 

 eggs, and two failed to deposit any eggs. Of the two that did not 

 deposit eggs, one was in copula 25 minutes and the other 10 minutes. 

 Each of these lived a short time and then died. The fecundity tests 

 of the remainder gave the results found tabulated in Tables V and VI. 



Table Y .—Fecundity of females of A. grandis in copula only one time and rendered 



fertile in that time. 





Time in 

 copula. 



Oviposition. 





Total 

 eggs. 



Eggs deposited. 



Eggs per day. 



Duration of fertility. 



Started. 



Ended. 



Period. 



Exter- 

 nally. 



Nor- 

 mally. 



Aver- j Maxi- 

 age. | mum. 



To end of oviposition . . 



To Aug. 10 



To end of oviposition. . 

 Do 



Minutes. 



24 



Mo 



26 



2 31 



29 



June 28 



...do 



June 30 

 July 12 

 Aug. 9 



Aug. 7 

 Aug. 27 

 July 18 

 Aug. 12 

 Sept. 4 



Days. 

 41 

 61 

 19 

 32 

 27 



348 

 456 



87 

 237 



32 







9 

 





 



348 

 447 



87 

 237 

 32 



U 



4.6 

 7.4 

 1 2 



17 

 21 



7 

 17 



Do 



3 







Total 



155 

 31 







180 

 36 



1.160 

 235 



9 



m 1,151 





Average 











Weighted average 











6.4 

 8.5 

 1.2 





Maximum 



45 

 24 







61 

 19 



456 

 32 



9 







447 

 32 



21 



Minimum 





3 





1 





i Copulated twice (22 and 23 minutes respectively) with interval of 12.5 minutes between copulations. 



2 Copulated four times (7, 4, 2, and 18 minutes respectively) between 10:04 a. m. and 11:18 a. m. Remain- 

 der of the weevils were in copula only one time. These copulations were with so very little time between 

 them that thev were considered as one fertilization. 



