Nov. 2s, 1918 Biology of Fruit-Fly Parasites in Hawaii 461 



fruit-fly pupa alone occurred, within which were the larval remains of 

 G. silvestrii. The remaining 183, puparia not having been parasitized by 

 G. silvestrii, produced 52 adults of D. tryoni, 14 of O. humilis, i of D. 

 jullawayi, 12 of T. giffardianus, 3 fruit flies, and the balance dried up 

 and produced nothing. Thus, in the 94 cases above cited, 72 occurred in 

 which a normal adult of G. silvestrii emerged as a hyperparasite on an 

 opiine parasite of the fruit fly. In 22 other cases it emerged as a normal 

 primary parasite of the fruit fly. 



As above mentioned, females of G. silvestrii will always oviposit into 

 larvae of Tetrasiichus giffardianus as they lie developing in the fruit-fly 

 puparium. T. giffardianus is a small parasite, being hardly one-half as 

 large as G. silvestrii. Its larvae are thus very small to receive the com- 

 paratively large egg of G. silvestrii. Larvae of T. giffardianus about 

 0.7 mm. long are oviposited into by G. silvestrii, and the egg, which is 

 about 0.35 mm. long, hatches and the larva of G. silvestrii develops, 

 pupates, and may ultimately produce a dwarfed adult about 1.5 mm. 

 long. The immature larva of T. giffardianus receiving the egg of G. sil- 

 vestrii is able to develop to maturity. It is killed, however, before it is 

 able to pupate. Females of G. silvestrii have actually oviposited into 

 larvae of T. giffardianus only 2 days old. In all of the experiments 

 conducted to prove the hyperparasitic action of G. silvestrii over T. 

 giffardianus, the eggs of the former were deposited into larvae of the 

 latter not more than 4 days old, the majority being only 2 and 3 days 

 old. 



On August 28 and 29, 191 7, a total of 209 mature fruit-fly larvae were 

 exposed to attack by T. giffardianus. All of these larvae formed into 

 puparia during the next two days. On August 31 these 209 puparia 

 were placed in a jar containing about 100 females of G. silvestrii and 

 left until September 2. On September 5, 6, and 7, 59 of the puparia 

 were opened, examined, and the contents carefully recorded. Each 

 puparium contained from 3 to 19 well-developed larvae of T. giffardianus, 

 and in every case from i to 6 of these larvae were dead and contained 

 an active larva of G. silvestrii in the first, second, or third instar. The 

 remaining 150 puparia were saved for adult emergences and ultimately 

 produced fruit flies, adults of both species, and in some cases both 

 species from the same puparium. 



Thus we have positive proof that this proctotrupid may be strongly 

 hyperparasitic upon any of the established parasites of the fruit fly that 

 are now contributing toward its control in Hawaii, and that it may act 

 with equal freedom as a primary parasite of the fruit, fly. 



PACHYCRBPOIDEUS DUBIUS 



A pteromalid, Pachycrepoideus duhius Ashmead, introduced from the 

 Philippines by Mr. D. T. Fullaway in 1914 as a dung-fly parasite, has 



