60 BULLETIN 351, U. S. DEPARTMENT OF AGRICULTURE. 



examination the male is often diverted and may move away, but 

 lie will return, again and again, before finally abandoning his efforts. 

 Those females that have copulated are indifferent to the male, but 

 females of the same age that have not copulated respond by elevat- 

 ing and distending the anal plates. After a preliminary examina- 

 tion of the dorsal surface of the female the male mounts and takes 

 the copulating position, with the head forward and the body paral- 

 lel to that of the female. In the act of copulation the abdomen is 

 curved under until the tip is in contact with the anal plates. The 

 act of copulation requires from 2 to 10 seconds, according to the 

 degree of exhaustion of the male. At the end of copulation the 

 male departs and continues his search for additional mates. If 

 by chance he returns a second time to the same female his tappings 

 bring no response. The male is decidedly polygamous and con- 

 tinues copulating with one female after another until he dies of 

 exhaustion. The following observations were made upon a male 

 that left the puparium September 6, 1913: 



Emerged from puparium 9.40 a. m. 



Discovered first susceptible female and copulated 9.42 a. m. 



Discovered second female and copulated 9.44 a. m. 



Discovered third female 9.46 a. m. 



Discovered fourth female . 9.50 a. m. 



Discovered fifth female 9.56 a. m. 



Died of exhaustion 9 p.m. 



At the end of the fifth copulation detailed observations stopped, 

 but the male continued in diligent search for more females. This in- 

 dividual died of exhaustion 12 hours after leaving the puparium. 



The active male, when moving naturally upon the host plant, lives 

 less than 24 hours. Almost invariably the male emerges in the fore- 

 noon, exhausts himself in copulation during the hottest portion of the 

 day, and dies before midnight. When confined singly in test tubes 

 they live from 1.25 to 2.75 days. Six specimens confined in test 

 tubes gave 2.75 days as the maximum, 1.25 days as the minimum, and 

 1.625 days as the average longevity. 



Summary of Life History of the Male. 



The male lives an average of 49 days and passes through 5 instars. 

 In the first two instars it is a vigorous feeder, and accumulates all 

 the energy used during the remainder of its life. The 3 remaining 

 instars are characterized, as a whole, by the absence of functional 

 mouth-parts and by the development of the adult organs. 



The length, in favorable weather, and the distinguishing character- 

 istics of the instars are as follows. 



The feeding instars: First instar, length 18 days — vegetative; 

 second instar, length 18 days — sexual differentiation. 



