WORK AND PARASITISM OF THE MEDITERRANEAN 

 FRUIT FLY IN HAWAII DURING 1918 



By H. F. WiLLARD 



Assistant Entomologist, in Charge of Mediterranean Fruit-Fly Quarantine Inspection, 

 Bureau of Entomology, United States Department of Agriculture 



The Mediterranean fruit fly (Ceratitis capitata Wiedemann) after its 

 introduction into Hawaii in 19 10 soon became the most destructive fruit 

 pest known in the history of the islands. A favorable climate, abundance 

 of host fruits, and the absence of effective control measures allowed it 

 to multiply so rapidly that it soon became established on all the important 

 islands of the Hawaiian group, where it greatly retarded their horti- 

 cultural development. Immediately after the discovery of the fly in 

 Hawaii, its importance as an enemy was recognized; and the Federal and 

 Territorial governments began to make exhaustive studies of its life 

 history and habits and to experiment with different methods of control. 



The use of natural enemies is the only control measure that has been 

 to any great degree successful. Since 191 3 the Hawaiian Board of Agri- 

 culture has introduced and successfully established in Hawaii four larval 

 parasites of Ceratitis capitata — namely, Opius humilis Silvestri, Diachasma 

 tryoni Cameron, Diachasma fullawayi Silvestri, and Tetrastichus gifjar- 

 dianus Silvestri. Every year since the establishment of these parasites, 

 the Bureau of Entomology has gathered and published exact data on 

 the degree of control exerted by them over the fruit fly, both as indi- 

 vidual species and collectively {1-4)} This series of publications will be 

 of value to entomologists who are interested in beneficial insects, by 

 giving them definite information regarding the seasonal and yearly suc- 

 cess achieved by each one of these four species. The taxpayer, who has 

 paid the expenses connected with the introduction of these parasites, 

 will find in these papers much definite information regarding the benefits 

 he is deriving from his investment. This paper, therefore, is a continu- 

 ation of these yearly records and gives the extent of parasitism during 

 191 8, the amount of infestation by C. capitata for the same period, and, 

 for purposes of comparison, general summaries of parasitism and infesta- 

 tion during 191 6 and 1917, taken from literature already cited. 



By reference to the data in Table I it will be seen that the infestation 

 during 1918 of a number of host fruits is as great as it was during 1917, 

 and in a few cases considerably greater. All these increases in infestation, 

 with the exception of that in the mango (Mangifera indica), have taken 



' Reference is made by number (italic) to " Literature cited. " p. 446. 



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



Washington, D. C. Jan. 15, 1920' 



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