MEDITERRANEAN FRUIT FLY IN HAWAII. 13 



the year in Honolulu. The presence of so much ripening fruit, 

 coupled with the favorable climatic conditions and the hardiness of 

 the fruit fly itself, has made the establishment of C. capitata and its 

 multiplication a most easy problem within the city limits. 



While the fruit fly finds host conditions most favorable within the 

 city limits, because of the large number of host trees and shrubs, 

 some of which are bearing at all seasons of the year, it has been able 

 to establish itself and multiply in the country, often miles from towns, 

 in some one or more of its hosts which have escaped cultivation, 

 and to have spread over uncultivated and uncultivable areas. Of 

 such hosts, the common guava (Psidium guayava) is the most 

 abundant. It has taken possession of the roadsides, pastures (PI. II), 

 vacant town lots, mountain gulches and hillsides, and even crevices 

 in precipices, from sea level up to 1,500 feet elevation. 1 So easily 

 does this plant grow from seed, and so thoroughly distributed are 

 its seeds by cattle, birds, and man, that it is seldom that a bush can 

 not be found within a stone's throw. In the lowland pastures and 

 mountain gulches up to an elevation of at least 1,300 feet, particularly 

 when sheltered from strong winds and well watered, the guava may 

 become very treelike and form dense thickets (PI. III). At higher 

 altitudes, and in wind-swept or arid areas, it may remain a low, 

 scrubby bush. While the guava fruits most heavily during the 

 spring and fall months, the bushes are continually blooming 

 and ripening a sufficient number of fruits to support the fruit fly 

 every month in the year. The writers are depending upon the illus- 

 trations to acquaint the reader, as words can not, with the well- 

 nigh universal distribution of this host and the wonderful oppor- 

 tunities it offers C. capitata for easy establishment and thorough 

 intrenchment. 



Second to the guava as a host occurring in wild, uncultivated areas 

 is the prickly-pear cactus (Opuntia vulgaris) (PL XVII). While the 

 fruits of this plant are not preferred by the Mediterranean fruit fly, 

 they are sufficiently infested in the absence of more favored hosts to 

 serve as food, and, as in the case of the guava, there is almost no 

 time during the year when a few ripe fruits may not be found in any 

 cactus scrub. 



Other host fruits, wild or escaped, are not so universally distrib- 

 uted. As a few, of the many examples, there may be mentioned a 

 grove of ball kamani trees in an isolated valley on the island of 

 Molokai, gulches overgrown with the passion vine (Passiflora sp.) 

 and the damson plum (ClirysophyTlum oliviforme) on the island of 

 Maui, the thickets of winged kamani growing along the windward 

 shores of the island of Qahu, and the wild coffee and mountain apple 

 (PL IV, fig. 1) in the forests of Oahu and Hawaii. 



1 Stunted bushes have been observed at 4,000 feet elevation. 



