Nov. 25. 1918 Biology of Fruit-Fly Parasites in Hawaii 443 



curred, resulting in the rearing of 114 males and 52 females. It has 

 been found possible to rear reasonable quantities of females under 

 various conditions of confinement. A large, well-lighted glass or screen 

 cage is strongly recommended. Cages less than 9 or 10 inches in 

 diameter, or even small glass tubes, can always be safely used for ovi- 

 positing females, but satisfactory mating does not occur in small cages. 

 From 100 males and 75 females placed, upon emergence, in a small 

 cage having a diameter of 2>2 inches and a length of 7 inches, a total of 

 558 males and 27 females was reared during their lifetime. This is an 

 average result in rearing this species when the cage is small. It shows 

 an abundant oviposition but little mating. 



Unmated females reproduce parthenogenetically, the progeny being 

 always males. These males have been proved fertile. 



OVIPOSITION 



Oviposition may commence upon the day of emergence. An average 

 of 80 mature eggs occurs in the ovaries of the newly emerged female. 

 The manner of egg deposition is similar to that described for Dia- 

 chasma tryoni. Only one egg is deposited at a time. An average 

 period of 17 seconds is required for the deposition of a single egg, after 

 the ovipositor has penetrated the fruit and located a larva. This is 

 based upon the timing of 31 separate egg depositions. The shortest 

 time was 10 seconds and the longest 3 minutes and 15 seconds. The 

 female attacks larvae in fruit on the ground as well as larvae in fruit on 

 the tree, she may oviposit into fruit-fly larvae in the second instar, and 

 selects no particular part of a larva in which to oviposit. The daily 

 rate of oviposition is indicated in Table V. Female 6 therein is of 

 unusual interest. A total of 255 eggs, deposited quite generally over 

 a period of 20 days, indicates that this species oviposits probably over a 

 longer period than does D. tryoni. The greatest number of eggs deposited 

 in 24 hours was 34. It is of interest that most of the individuals shown 

 in Table V died shortly after the last egg was deposited. Female 6 

 was given, in addition to honey and water in the proportions of i part 

 honey to 6 of water, a daily feeding of pure water. During the morning 

 hours nothing but water was given, the honey being added in the after- 

 noon. All of the parasites used in the oviposition records were confined 

 in glass cylinders 6 inches long and i inch in diameter, open at both ends 

 but protected with screened caps. Unparasitized fruit-fly larvae reared 

 in the laboratory were used in obtaining the records. The larvae were 

 daily placed in the fruits of Mimusops elengi (Plate 32, A) and were 

 removed daily thereafter and dissected, under magnification, for eggs 

 of the parasite and replaced daily by others so that the experiment 

 might be continued until the death of the females. 



