76 



SEXUAL ATTKACTION AND DURATION OF COPULATION. 



The distance through which the attraction of the female insect will 

 influence the male varies extremely. To ascertain how far the attrac- 

 tion might be exerted in the case of the boll weevil, 2 females were 

 confined with food in a small bottle covered with cheese cloth, and the 

 bottle was then placed in a horizontal position inside a field cage and 

 near its top. Within this cage were 3 males which had been confined 

 there alone for 4 weeks. The bottle containing the females was so 

 placed as to be within a few inches of the top of a cotton plant upon 

 which the males were working and touching the leaves of the plant, 

 in order to afford the males access to the bottle without having to fly 

 to it. 



Close watch was kept, but during 11 days not a male was seen to 

 go near the bottle. At the end of that time the females were taken 

 into the laborator}^, as was also one of the males from the cage. All 

 were removed from squares and, being placed upon the table, were 

 brought gradually nearer together. The male paid no attention what- 

 ever to the nearer female until brought within an inch of her. He 

 then went directly to her. The sense of smell appeared to guide his 

 movements. The fact that this male mated readily with both of the 

 females used in the cage shows that the only reason for failure to 

 attract in the cage lay in too great distance separating the sexes. 



These observations are entirely borne out by those made in the field. 

 The fact appears to be that the sexes are attracted only when they 

 meet, as they are likely to do, either on the stems or upon the squares 

 of a plant. The comparative inactivity of the male may have some 

 relation to this matter. The general conclusion is that instead of 

 seeking widely for the females, the males are content to wait for them 

 to come their way. The greater comparative activity of females is 

 shown in the study of their food habits. 



In a considerable number of cases that were timed the average dura- 

 tion of the sexual act was very nearly thirty minutes. 



DURATION OF FERTILITY IN ISOLATED FEMALES. 



A number of females which were known to have mated were isolated 

 to determine this point. Although neither limit was exactly deter- 

 mined, the results proved very striking. Several of these females 

 laid over 225 eggs each and nearly all of them proved fertile. Select- 

 ing three cases in which the facts are positively known, it appears that 

 fertilit}^ lasted for an average of something over 66 days and that 

 during this period these females deposited an average of nearly 200 

 eggs. The maximum limits may possibly be considerably higher than 

 these. A single union seems to insure the fertility of as many eggs as 

 the average female will lay, and its potency certainly lasts for a period 

 fully equal to the average duration of life. 



