Nov. 25, 1918 Biology of Fruit-Fly Parasites in Hawaii 433 



ference. In pressing and working the head through this cut the entire 

 end of the puparium usually is broken off and the parasite quickly 

 emerges (fig. 17). In a few moments the antennae, legs, and ovipositor 

 straighten out. Immediately upon emerging the meconium is dis- 

 charged. The period in the development of parasitic Hymenoptera 

 when the meconium is discharged is interesting. With the opiines 

 treated in this publication the meconium is never voided until the adult 

 emerges. In the eulophid Tetrastichus gifjardianus a major meconium 

 is discharged just after the emergence of the adult and there is a barely 

 perceptible discharge during the prepupal period; The pteromalid 

 Pachycrepoideus dubius and the proctotrupid Galesus silvestrii void a 

 large quantity of waste while in the prepupal stage and later, upon 

 emergence, void an insignificant meconium. 



Males nearly always commence emerging before the females and 

 usually are all out while the females are still actively emerging. The 

 period of greatest emergence 

 of the males is from two to ^-7'"'^'7''''7'^ 



three days earlier than is 

 that of the females. After 

 leaving the puparium noth- 

 ing can be found of the 

 pupal skin. It is so ex- 

 tremely thin as to be almost 



invisible in water beneath Fig. 17. — Diachasma tryoni-. Fruit fly puparium showing 



1 "R -f fin emergence hole made by adult parasite. Length 4 mm. 



a cover glass. ±5eiOre tne Typical of exit hole made by Z?./!(.«aa'a:>'!' and 0/>m^ a wwzife. 



adult emerges, however, the 



pupal skin can be torn from the pupa as a thin, transparent covering. 



Copulation takes place most frequently during the first few days 

 after emergence. In the laboratory mating has been repeatedly observed 

 within 5 to 10 minutes after the adults have come out. The copulation 

 period is short. It lasts from about lo to about 60 seconds. The sex 

 attraction is most strongly evident in the male. Practically all activity 

 prior to and coincident with mating is on the part of the male. It 

 becomes greatly excited when within i to 3 inches of the female and 

 vibrates the wings rapidly and spasmodically. The male emits a strong, 

 sweet odor. It is greatest in intensity in the presence of the female. 

 No perceptible odor issues from the female. It never shows any great 

 interest in the male and can readily repel it with the posterior pair of 

 legs. In glass tubes the males make no distinction between mated 

 and virgin females. Weak or injured females, unable to repel the male, 

 may mate an indefinite number of times. A male may successfully 

 copulate with different females more than once within a short period. 

 A freshly emerged male was observed to mate with different females 

 on August 24, 1 91 7, at 10.20 a. m.,^ 10.25 ^- m-, and 11.05 a. m. Normal 



• All references to clock time relate to "standard time." 



