154 



of pupae obtained for experimental purposes, samples wliich were 

 placed in covered jars. These samples were allowed to remain in 

 their containers until all emergence had ceased, when they were 

 emptied separately into large pill boxes, properly labelled, and set 

 aside until such time as the laboratory force could make the 

 counts necessary to determine the percentages of parasitism. Since 

 the few examinations that Avere made during July indicated that 

 the average parasitism did not exceed 3 per cent, the percentages 

 just determined are a pleasant surprise, and are here presented, 

 at your request, and with the approval of the Federal Bureau. 

 While it is too early yet to predict that the Mediterranean Fruit 

 Fly w^ill be satisfactorily controlled by introduced parasites, there 

 can be no question but that the South African parasite, Opius 

 humilis, alone, is partially, if not entirely, responsible for the 

 noticeable decrease in fruit fly abundance in certain localities, 

 and that the moneys appropriated by your Board for parasitic 

 work have already yielded most gratifying results. 



In presenting these data on parasites it should be mentioned 

 that all have been obtained from material gathered within the 

 limits of Honolulu with the exception of those resulting from an 

 investigation of the fruit fly in coffee in the Kona District during 

 October and JNTovember. Aside from the comparatively few speci- 

 mens of the Australian parasite, Diachasma tryoni, bred from the 

 Kona material no introduced parasite has been bred but the 

 South African, Opius humilis. As no specimens of this latter 

 species were liberated on the Island of Oihu previous to JSTovem- 

 ber and December, 1913, the Honolulu data form a distinct addi- 

 tion to our knoAvledge of the multiplication of this parasite during 

 the first year after its liberation, and will play an important part 

 ill determining the increase in its efliciency during coming years. 



Before introducing the percentages to which reference has 

 been made, the writers wish to bring out two additional points : 

 first, that during the year and a half previous to the liberation 

 of introduced parasites in Honolulu, and previous to the libera- 

 tion of these parasites at any other points in the Islands where 

 federal work had been carried on, the writers had at no time 

 bred Opius or Diacliasma, whereas at the time of this writing 

 (December, 1914) parasites are bred from practically every lot 

 of fruit flies brought to the laboratory from localities where par- 

 asites have been liberated; second, that complete justice is not 

 done the parasites in every instance recorded in Tables II to Y. 

 This is due to the fact that both Opius hiimilis and Diachasma 

 tryoni parasitize only, or for the most part, the medium sized or 

 well grown larvae of the fruit flv. Thus if any lot of fruit be 

 placed in a coijtainer and allowed to remain until all larvae have 

 emerged and pupated, the percentage of parasitism obtained from 



