INTERRELATIONS OF FRUIT-FLY PARASITES IN HAWAII 



By C. E. Pemberton, Assistant Entomologist, and H. F. Willard, Fruit-Fly Quar- 

 antine Inspector, Mediterranean Fruit-Fly Investigations, Bureau of Entomology, 

 United States Department of Agriculture 



INTRODUCTION 



The introduction and ultimate establishment of four species of larval 

 parasites of the Mediterranean fruit fly {Ceratitis capitata Wied.) in 

 Hawaii, wherein exist ideal conditions for the rapid and unchecked 

 development of the host throughout the year, has opened an exceptional 

 opportunity for an investigation of all phases of the work of these para- 

 sites, not only in their relations to the host but also to one another, and 

 has made possible the determination of many points of unusual interest to 

 biological students of insect parasitism and of particular value to ento- 

 mologists dealing with considerations relating to general parasitic control 

 of insect pests. ^ 



The information herein presented is given, not as a final decision or 

 positive argument against the introduction of many parasites of a single 

 pest, but to reveal the actual need for careful biological studies of para- 

 sites, especially in their interactions upon one another, before general 

 ntroductions or liberations can be intelligently undertaken. 



Entomologists, detailed in the past for researches in insect parasitism 

 in foreign countries, have customarily adopted the policy of assembling 

 all available species of primary parasites of the insects under investiga- 

 tion, with the final intention of conveying them all to the home country 

 for propagation and liberation. The chief caution of these workers has 

 usually been the elimination of all secondary parasites from the material 

 prepared for shipment. Admirable results have often been achieved. 

 However, after the introduction of several species, through one or suc- 

 cessive importations, few, if any, considerations have been given to the 

 possibility of detrimental results arising from interference with the action 

 of one parasite of primary importance and great prolificness by another 

 of less value and proved inferiority. 



The important bearing that a preliminary and detailed knowledge of 

 parasite habits may have upon the general question of parasite importa- 

 tions has already been well directed to the attention of entomologists by 

 Dr. L. O. Howard. He states ^ that— 



It is unwise and most unpromising to attempt heterogeneous and miscellaneous 

 importations of parasites without careful study of the host insect on its home ground 



1 For a history of these parasitic introductions and a discussion of climatic and host relationships favor- 

 jng parasitic increase, see Back, E. A., and Pemberton, C. E., the mediterranean fruit fly in 

 HAWAII. U. S. Dept. Agr. Bull. 536, 119 p., 21 pi., 24 fig. 1918. 



s Howard, L. O. the practical use op the insect enemies op injurious insects. In U. S. Dept. 

 Agr. Yearbook 1916, p. 282. 1917. 



Journal of Agricultural Research, Vol. XII, No. 5 



Washington, D. C. Feb. 4, 1918 



jr Key No. K— 60 



(28s) 



