116 BULLETIN 536, U. S. DEPARTMENT OF AGRICULTURE. 



SUMMARY. 



The Mediterranean fruit fly (Ceratitis cajritata) was discovered at 

 Honolulu in the Hawaiian Islands in 1910. Since that time it has 

 spread to all the islands of the Hawaiian group, and because of the 

 equable climate and abundance of host fruits, has effected a serious 

 and permanent check to horticultural pursuits, and put an end to all 

 export trade in fruits except that in bananas and pineapples. 



Research seems to have fixed the native home of C. capitata in 

 tropical Africa. Its spread has been slow but persistent throughout 

 tropical and semitropical countries, until at the present time it is 

 known to have become a pest in every continental area except that 

 of North America. With the Mediterranean fruit fly now well 

 established in Bermuda and the Hawaiian Islands, it would seem that 

 it is only a matter of time before it will be inadvertently introduced 

 and become established in California and the Southern States. The 

 frequent interception and destruction of infested fruits from Hawaii 

 at California ports, by officers of the Federal Horticultural Board, 

 indicates the ease with which the introduction of the Mediterranean 

 fruit fly might occur were Hawaiian fruit permitted unrestricted 

 entry to the mainland of the United States. 



No edible fruit in Hawaii, except the pineapple, escapes attack. 

 The banana, when in good condition, is never infested, infestation 

 having been noted only when the fruits were overripe or injured. 

 The Mediterranean fruit fly has been reared in Honolulu from 72 

 species of host fruits, including the peach, plum, pear, guava, mango, 

 orange, lemon, grapefruit, banana, etc. A large proportion of the 

 host fruits are inedible. Throughout the littoral regions a continu- 

 ous cycle of host fruits is available for infestation throughout the 

 year; hence there are no starvation periods for the fly to survive. 



With such a quantity and variety of host fruits, nuts, and vege- 

 tables in which to propagate, and enjoying an ideal climate, the 

 mean temperatures of which vary between 68° and 79° F. for the 

 regions in which the fly is a most serious pest, the Mediterranean 

 fruit fly finds no check to its rapid increase. While a single genera- 

 tion may require as few as 17 days during the warmest weather, 

 there are usually 15 to 16 generations a year at Honolulu, and 10 to 

 12 generations in areas where the winter mean drops to 68° F. There 

 is considerable variation in the length of the immature stages, par- 

 ticularly during the coolest weather. Inasmuch as adults have been 

 kept alive for 10 months and may deposit eggs in lots of a few to 32 

 daily quite regularly throughout life, the generations become hope- 

 lessly confused. While adults are not forced in Hawaii to pass 

 through periods of several months when food is not available for 

 oviposition, females deprived of host fruits for such periods will 

 resume active and normal oviposition when the fruits become avail- 



