Nov. 25, 1918 Biology of Fruit-Fly Parasites in Hawaii 45 1 



in the puparium for many hours before an opening is cut through which 

 they can escape. Males and females all appear to emerge at the same 

 time, for as soon as a sufficiently large exit hole is made, the adult 

 flies come out as quickly as possible, irrespective of sex. The males 

 remain hovering about the puparia but the females immediately crawl 

 away. The meconium, which is developed and retained in the mid- 

 intestine by the larva and held there in the pupa stage, is voided by the 

 adult immediately upon emergence. 



Mating occurs as soon as the adults are out of the puparium. The 

 entire process occupies only a few seconds. Females once mated have 

 no difficulty in warding off the males. No mating occurs within the 

 puparium even though the parasites may be actively moving about in 

 it for several hours before they escape. This is proved 

 from the fact that all females taken immediately after 

 emergence and isolated produce parthenogenetic males. 

 One male may mate with several females withiji a few 

 hours. On September 8, 191 6, one male was placed with _^_ 



8 virgin females and left for four days. Each female r 'oSr 

 was then placed in a separate vial and given opportu- 

 nity to oviposit. All produced both male and female 

 progeny. That the male is particularly capacitated for 

 frequent mating is to be expected when the proportion 

 of the sexes is considered, the females always greatly 

 outnumbering the males. During 191 6 and 1917a total 



1 J „ P 1 o , 'Pio. 2,i—Tetrasiichlis 



of 13,114 males and 47,804 females, or 78.5 per cent, giffardianus: v^mi- 

 emerged from fruit-fly puparia collected in the field ^^ puparium 



- , showing character- 



about Honolulu. istic emergence 



Unmated females are always arrhenotokous. From hole made by adult 

 the proportion of sexes secured from field collections, it 

 is shown that the smaller proportion of males readily gain access to and 

 mate with the much larger proportion of females. 



OVIPOSITION 



Females niay begin ovipositing as soon as they emerge, whether mated 

 or not. The mature pupa has well-developed eggs in the ovaries. Four- 

 teen newly emerged females when examined October 20, 191 7, contained 

 73, 70. 72, 60, 72>, 66, 71, 81, 65, 45, 58, 64, 61, and 52 mature eggs, re- 

 spectively. The method of oviposition is best understood by an exa«m- 

 ination of Plate 32, B, C, and D. The female enters the fruit wherever 

 access can be gained through holes, decayed spots, or breaks on the 

 surface. There is no evidence to indicate that the parasite bares into 

 firm pulp or into the skin of the fruit. Once into the fruit, however, the 

 female may become attached to a larva and be drawn through all manner 

 of pulp and juice before her object has been attained. As soon as a 

 larva is located, the ovipo&itor is quickly brought forward and beneath the 

 83817°— 18 3 



