JOma OFAGEETlMgARCH 



Vol. XV Washington, D. C, November 25, 1918 No. 8 



A CONTRIBUTION TO THE BIOLOGY OF FRUIT-FLY 

 PARASITES IN HAWAII 



By C. E. PEMBERTON, Entomologist in Field Charge, and H. F. Willard, Chief Fruit- 

 Fly Quarantine Inspector, Mediterranean Fruit-Fly Investigations, Bureau of Ento- 

 mology, United States Department of Agriculttire 



INTRODUCTION 



With the termination of an intensive study of the Mediterranean fruit 

 fly (CeratiHs capitata Wiedemann) in Hav/aii in February, 191 6, by the 

 Bureau of Entomology, a general investigation of the biology, interrela- 

 tion ^ and economic value of introduced parasites of this fruit fly was 

 begun. The results of this investigation are herewith presented. 



The natural enemies of the Mediterranean fruit fly now contributing 

 toward its control in Hawaii are three species of Opiinae — viz, Diachasma 

 tryoni Cameron, Opius humilis Silvestri, and D. fullawayi Silvestri, one 

 species of Blilophinae, Tetrastichus gifjardianus Silvestri, and an ant, 

 Pheidole megacephala Fabricius. Two other parasites occasionally reared 

 from the fruit fly are Opius fletcheri Silvestri, normally a melon-fly para- 

 site, and Pachycrepoideus duhius, a dung-fly parasite. At present para- 

 sitism by these two parasites is not important, and may be more acci- 

 dental than normal. The opiines and the eulophid are strictly larval 

 parasites. The ant is important as a predacious enemy of the larvae and 

 to a lesser extent of the pupae. The pteromalid Pachycrepoideus duhius 

 attacks the pupa. There is striking similarity in habit, structure, and 

 development among the opiines under discussion, and in view of this the 

 species now most abundant in Hawaii, Diachasma tryoni, will be dealt 

 with the most completely, to be followed by notes on the special features 

 of the two other important opiine species together with comparisons with 

 the species tryoni in sufficient detail to give a thorough conception of the 

 biology of each.- 



' For previous studies on fruit-fly interrelations in Hawaii, see Pemberton and Willard {6). [Refereoce 

 is made by number (italic) to " Literature cited," p. 465.] 



* For the original descriptions and history of the introductions of the important species above mentioned, 

 see Back, E. A., and Pemberton, C. E. (3). 



For detailed records on the extent of parasitism in Hawaii by these species see Back and Pemberton 

 (i, 2) and Pemberton and Willard (5). 



Journal of Agricultural Research, Vol. XV, No. 8 



Washington, D. C. Nov. 25, 1918 



qh Key No. ^-73 



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