THE MEDITERRANEAN FRUIT FLY. 



39 



PARASITES. 



The very climatic and host conditions that have made the Medi- 

 terranean fruit fly an unusually serious pest in Hawaii and that, 

 with crop conditions as they are, have made artificial methods of 

 control impracticable, have been most favorable for an attempt 

 at control by means of parasites. An abundance of the fruit fly upon 

 which to feed and a climate permitting increase each month in the 

 year have made conditions ideal. The search for and discovery of 

 parasites, and their introduction and establishment where previously 

 there had been none, has been one of the entomological romances of 

 the present time. The 

 parasites now at work 

 killing the fruit fly in 

 Hawaii have been in- 

 troduced by the Ha- 

 waiian Board of Agri- 

 culture and Forestry as 

 a result of the Silvestri 

 and the Fullaway- 

 Bri dwell expeditions 

 to Africa. 



These two expedi- 

 tions resulted in the 

 establishment in the 

 islands between May, 



1913, and October, 



1914, of four promis- 

 ing parasites : one from 

 South Africa, 1 one 

 from eastern Austra- 

 lia, 2 and two from 

 Nigeria, 3 West iUrica. 

 Of these, only one, the 

 South African Opius, 

 was discovered as a 

 parasite of the Mediterranean fruit fly. The three others were found 

 parasitizing other fruit flies, and they have adapted themselves 

 in Hawaii to the Mediterranean fruit fly. None of them, however, 

 has been known to attack the melon fly in the gardens in 

 Hawaii. Large numbers of all the parasites have been reared and 

 have been liberated in all parts of the islands, until to-day they are 

 well able to care for themselves. They have multiplied with 

 remarkable rapidity and have unquestionably reduced the numerical 



Fig. 30.— Diagrammatic drawing of a cross section of a coffee cherry 

 to illustrate comparative ease with which the South African para- 

 site can lay eggs in the fruit-fly larva: a, Coffee bean; b, pulp 

 destroyed by maggot; c, skin of cherry; d, maggot of fruit fly; e, 

 parasite forcing its stinger through skin of cherry into maggot. 

 (Original.) 



Opius humilis Silv. 2 Diachasma tryoni Cam. s D.fullawayi Silv. and Tetrastichus gifi'ardianus Silv. 



