THE MELON FLY IN HAWAII. 55 



SUMMARY. 



The melon fly {Bactrocera cucurbitae Coq.) is found well dis- 

 tributed over India, which is considered its native home. It is at 

 present found in India, Ceylon, Java, Timor, Northern Australia, 

 Singapore, the Philippine Islands, southern China, Japan, and th<^ 

 Hawaiian Islands. It was introduced into the Hawaiian Islands 

 from Japan about 1895, and by 181)7, when it was first observed, it 

 was already a serious pest. Up to the present time it has been 

 allowed to increase unrestricted, and because of the equable climate 

 and abundant food supply has become a serious pest of cucurbitaceous 

 crops, cowpeas, string beans, and tomatoes. It is impossible to over- 

 state the destructiveness of the melon fly to cucurbitaceous fruits 

 under Hawaiian, littoral conditions, where these can be brought to 

 maturity only with the exercise of the greatest care on the part of 

 market gardeners. 



It has been estimated that the melon fly causes a loss of about three- 

 quarters of a million dollars in a territory smaller than the State of 

 Rhode Island. It is a pest of prime importance that is being inter- 

 cepted each year by officers of the Federal Horticultural Board in 

 ships arriving at the California coast from Honolulu and Hilo, and 

 there is, therefore, great danger of the melon fly being introduced to 

 the continental United States. 



During the warmest seasons in Hawaii, when the mean tempera- 

 tures average about 79.5° F., the egg, larval, and pupal stages may 

 be passed in as few as 12 or as many as 28| days, according to the 

 individual and host conditions. At mean temperatures lower than 

 79.5° F. the duration of the immature stages may be greatly in- 

 creased. Thus at 51.6° F. the pupal stage alone may require 59 days 

 and the egg 11 days, while at 56° to 62° F. the first and third larval 

 stages may require 27 and 23 days, respectively. Under varying 

 conditions of host, temperature, and humidity the immature stages 

 may be lengthened from a minimum of 12 days to 3^ to 1 months. 

 Adults may live as many as 131 days, although the duration of adult 

 life is variable and may be but a few days. Adults deprived of food 

 and water never live more than 102 hours or more than 120 hours 

 without food but with water. This is also true of adults which have 

 been feeding for some time when placed under starvation conditions. 

 The complete life cycle may, therefore, occupy from 143 to 159 days 

 in the case of most hardy individuals passing the egg, larval, and 

 pupal stages during the warmest seasons, but longer when these stages 

 are passed during colder seasons. 



Adults feed principally upon the juices of host plants, nectar of 

 flowers, and honey dew secreted by a large number of insects. While 

 the melon flies are rapid fliers and are found often far from their 

 host plants, they appear to arrive at these points as the result ©f 



