THE MELON FLY IN HAWAII. 23 



of sexual activities within three or four days after emergence, and 

 begin ovipositing soon thereafter, the writers were at loss to explain 

 the apparent indifference to each other of the sexes of the melon 

 fly. It was thought for a time that failure to secure evidence of 

 sexual activity might be due to improper confinement or feeding, and 

 a number of lots of adults were discarded before it was discovered 

 that melon flies mate only at dusk and only after they have become 

 somewhat older than adults of Ceratitis capitata. 



Eecent feeding experiments with the melon fly have shown that 

 certain foods may play an exceedingly important part in the stimula- 

 tion of bodily forces, sexual activity, and egg maturation. These 

 experiments have shown that the use of fresh cucumbers, cut open 

 and kept constantly in the jars containing the adults, would so 

 accelerate the development of the reproductive system that copula- 

 tion commenced as early as ten days after emergence from the pupal 

 stage. Thus, in four lots of flies emerging on October 24, 27, 28, 

 and 29, 1916, comprising a total of 1,230 adults, mating commenced 

 with a few individuals in each lot, successively, at sunset, the tenth 

 clay after emergence, the mean average temperature being 76.4° F. 

 and the mean relative humidity 69.1 per cent. This is a most striking 

 condition when comparison is made with the ages at time of first 

 mating of adults that are confined in jars of similar size, but fed on 

 papaya and water or sugar and water. Many hundreds of adults 

 kept in confinement during the years 1913, 1914, and 1915 in Hono- 

 lulu and fed on papaya and water were never seen to mate before 

 20 days after emergence. Thus, out of about 200 individuals emerg- 

 ing on May 24, 1914, which were fed on papaya and water one pair 

 was noted in coition for the first time on June 13, or 20. days after 

 emergence. Among a second lot of adults, emerging on May 23 and 

 similarly fed, no adults mated until Ju«ne 16, when two pairs were 

 seen mating. The majority of females in these lots did not mate 

 until they were fully 25 days old. The daily mean temperature for 

 the period from May 23 to June 16 averaged 75.5° F., while the mean 

 relative humidity averaged 69.3 per cent. Individuals of another 

 lot of flies emerging January 3, 1916, and fed on papaya and water 

 showed no indications of mating until early in February. The lower 

 average mean temperature of 71° F., and the higher mean relative 

 humidity of 78.5 per cent of January, were responsible for the greater 

 period required for the beginning of sexual activity. 



Evidences of sexual activity begin during the warmer months only 

 at about sunset. From sunset until darkness the sexes are in a state 

 of intense activity. Both sexes dart rapidly about the containing 

 jar and in their efforts to copulate produce much confusion. Pairs 

 remain in coitu, in some instances, until daybreak. Females mate 

 frequently and with different males. 



