THE MELON PLY. 7 



established and serious pest throughout all the coastal regions. It 

 has been known even to attack cucumbers and squash at altitudes 

 ranging up to 4,000 or 4,500 feet. 



METHODS OF SPREAD. 



The melon fly probably is carried more often from one locality 

 or country to another in the larva stage than in any other form. 

 Quarantine officials at San Francisco have found living larvae in 

 host fruits arriving at San Francisco on ships from Honolulu, and 

 records prove that the melon fly in the larva stage is able to bridge 

 the six or seven days required by the slower vessels to cover the 2,000 

 miles between the Hawaiian Islands and California, since infested 

 fruits have been intercepted and condemned at least once a year 

 since 1912. Host fruits taken on board ships as ship's stores are 

 capable of carrying the melon fly as larvae, or later as pupae, in the 

 fruit containers, for voyages occupying a longer time than is re- 

 quired to cross the Pacific Ocean, and thus may become a factor in 

 spreading the pest through vessels plying between almost all coun- 

 tries where climatic conditions are favorable for the establishment 

 of the fly. 



The spread from one country to another at a considerable distance 

 probably starts with the fly in the larva stage, but the spread from 

 town to town, or over short distances, as between islands of the 

 Hawaiian group, may occur in the adult or pupa stage. A female fly 

 has been observed to alight on an automobile top and be carried 16 

 miles from the country into the city of Honolulu. On another occa- 

 sion an adult was seen flying about an interisland boat en route from 

 Honolulu to Hilo, on the island of Hawaii. This fly was not observed 

 after the boat weighed anchor at the port of Lahaina, on the island 

 of Maui, or 72 miles from Honolulu. These two instances will ex- 

 plain the spread of the pest, in the adult stage, about the islands of 

 Hawaii, even if it could not be transported in the larva stage. . 



When larvae form their puparia on bare surfaces, and particularly 

 on a cloth surface, the puparia may adhere sufficiently well to make 

 it possible for them to be transported considerable distances under 

 favorable circumstances. Although no definite instances are known 

 where the melon fly has been spread thus, distribution in this fashion 

 is quite feasible and to be expected. 



ECONOMIC IMPORTANCE. 



The melon fly is the most important pest of varieties of melons, 

 squashes, and curcurbits in general grown in the Hawaiian Islands, 

 md probably elsewhere. Its persistent attack has caused many per- 

 sons to abandon the growing of the more susceptible host fruits. 



