44 The Philippine Journal of Science 1913 



perature of 20° C. to 23° C. No special provision was made for 

 moisture in the tubes. Under these conditions the maximum 

 period of life was seventy-two days. This was a female. 



In the tests with laboratory-bred flies, which emerged about 

 the middle of July, 63 flies were employed. Twenty-four males 

 had an average longevity of twenty-eight days, while 39 female 

 flies lived for an average of thirty-two days. Six of the females 

 showed an average longevity of fifty-four days, and 6 of the 

 males averaged thirty-nine days. One female of this series lived 

 seventy-two days, while 1 male lived fully ninety-four days. 



Perhaps a fairer method to determine the natural longevity 

 would be to mark thousands of bred flies and set them free, 

 and from time to time, through systematic collecting, attempt 

 to recover them. 



MATING 



The mating of Stomoxys calcitrans was never observed under 

 field conditions except in one instance where a pair was observed 

 in copulation while the female v;as attempting to feed. The 

 process was observed in bred flies in 3 instances, occurring in 

 2 pairs upon the seventh day after emerging from the puparium. 

 As has been noted previously, two days after the copulatory 

 act, fertile eggs were laid. These flies had been kept in com- 

 pany with many others in a large bottle which was daily applied 

 to a monkey for feeding purposes. 



In the act of mating the male assumes the active role, flying 

 oft" after a period of ten minutes. In these flies the male is 

 above, almost at right angles, adhering only by the genitalia and 

 front legs, the other legs being suspended at each side. The 

 clasping organ of the male exerts a pressure upward and for- 

 ward, the female genitalia respond in a backward and down- 

 ward movement, resulting in a quick, decided telescoping of 

 the parts. The male withdraws the intromittent organ by a 

 downward pull at the conclusion of the process. It releases its 

 hind legs and flies away directly while the female remains for 

 a few minutes. During this time a reflex telescopic action takes 

 place until the invaginated parts, which have been depressed, 

 are extended to their normal length. 



METHODS EMPLOYED IN KEEPING AND FEEDING FLIES FOR 

 LABORATORY PURPOSES 



The methods employed for keeping and feeding Stomoxys in 

 captivity will serve for other species of blood-sucking flies; for 

 example, species of Lyperosia and of the Hippoboscidae. The 



