92 



In the male the ofenitalia are quite peculiar and consist of two fan- 

 like lamellae, thickly fringed with long pale ochraceous hairs, which 

 partially inclose the claspers (fig. 11). When everted the tufts of 



yellow hairs are very noticeable, but at rest 

 they are almost completely retracted within 

 the abdomen. 



Copulation was observed only once, in a 

 small bottle and under very abnormal condi- 

 tions. The moths were united end to end, 

 as is the usual habit among moths. Many 



Fig. ll.-Genitalia of male bollworm other individuals have CODulated in the breed- 

 moth (original). . . • .1 1 U i U ^ 1 



mg ]ars m the laboratory, but never when 

 under direct observation. 



PROPORTIONS OF THE SEXES. 



A number of observations were made and data concerning over 300 

 moths were collected which bear evidence on the proportions of the 

 sexes. These include records of moths collected in the field and of 

 those bred out in the laboratory. In practically all cases there is a 

 slight preponderance of females in the ratio of 168 females to 120 

 males. Since the sexes are not readily distinguished externally, that 

 of each specimen was determined by dissection. It might be suggested 

 that the small number of males may be due to their greater agility in 

 eluding capture in the field, but the records from the laboratory 

 breeding do not bear out such a conclusion. 



/ LENGTH OF LIFE. 



The life of the moths seems to be determined almost entirely by the 

 external conditions after emergence, especially by the supply of 

 available food. During the season some eighty specimens were kept 

 in breeding jars in the laboratory and subjected to variable conditions 

 in order to ascertain the length of life. A short summary of the 

 results is given in the table below. 



Table XXXVI. — Average length of life of moths in lahorator;/, 1904- 



Month. 



May 



June 



July 



August 



September 

 October . . . 



Males. 



Females. 



With 

 food. 



Without 

 food. 



With 

 food. 



Without 

 food. 



Days. 



12 

 10 



lOi 



Days. 

 3* 

 4^ 

 4 

 4 



Days. 

 9i 

 16 

 12 

 13 

 18 

 Hi 



Days. 

 6i 

 3 

 6 

 6 











Longest life of males, 19 days 12 hours, during September. 

 Longest life of females, 38 days, during September-October, 



