MEDITERRANEAN FRUIT FLY IN" HAWAII. 27 



13. Chinese Inkberry (Cestrum sp.). 



The Chinese inkberry (Cestrum sp.) is seldom infested, although the trees produce 

 an abundance of fruit. Samples of several hundred fruits, each taken from the ground 

 among badly infested coffee trees, have yielded no adults. In one instance 3 adults 

 were reared from fruits collected by the Hawaiian Board of Agriculture in Manoa 

 Valley in November, 1911. 



14. Star Apple (Chrysophyllum cainito). 



The star apple (Chrysophyllum cainito) is a preferred host and is always grossly 

 infested. The writers have not observed a single mature fruit during the past three 

 years that was uninfested. The milky, sticky juice exudes from abrasions in the skin 

 until the fruit is overripe. Often, as is the case with other species of Chrysophyllum, 

 this juice solidifies so rapidly that the female fruit fly is caught by the ovipositor and 

 held captive until death. From four very ripe fruits collected at Haleiwa, May 30, 

 1913, 188, 110, 105, and 5 adults, respectively, were reared. Five fruits from the 

 same tree, picked May 27, 1914, yielded 18, 96, 54, 105, and 44 adults, respectively. 



15. Damson Plum (Chrysophyllum oliviforme) . 



The small plum Chrysophyllum oliviforme is one of the preferred hosts of C. capitata. 

 Like its relative, the star apple (Chrysophyllum cainito), it is well protected by the 

 white sticky juice which exudes rapidly from breaks made in its skin until quite 

 well grown. (PI. VIII, fig. 3.) Although larvae develop to a very large size in this 

 fruit and scarcely a fruit ripens uninfested, the average number of larvae per fruit is 

 small. Of a sample of 48 fruits collected during Februaiy, 18 produced no adult flies. 

 From the remaining 30 fruits an average of 2.4 adults resulted, 14 being the largest 

 number of adults reared from a single fruit. 



16. Chrysophyllum polynecium. 



This fruit, which is round and about half an inch in diameter, is congeneric with the 



star apple (Chrysophyllum cainito) and the Damson plum (Chrysophyllum oliviforme). 



Like them it is a preferred host and always grossly infested. From two lots of 500 



fruits each gathered from the ground during May, 1914, 1,584 and 1,140 adult flies were 



reared. 



17-26. Citrus Fruits. 



In a previously published paper x on the susceptibility of citrus fruits, the writers 

 present data secured under Hawaiian conditions which show why such thin-skinned 

 fruits as the tangerine, mandarin, Chinese orange, and kumquats are readily infested, 

 and why oranges, lemons, and grapefruit resist infestation of the pulp with such remark- 

 able success. All varieties of citrus have been found in Hawaii containing well-grown 

 larvae of C. capitata in their pulp and first-instar larvae transferred to the sourest, and 

 even half-grown lemons have been reared to the adult stage, so there is no question as 

 to the correctness of classifying all citrus fruits among the hosts of C. capitata. While 

 it seems evident that the acidity of partially ripe lemons has a detrimental effect upon 

 larval growth, it has been proved experimentally and by field observation, both bj r 

 Quayle and the writers, that no fruit is too acid for larval development. Savastano, 

 in 1914, giving the results of experimental work carried on in Italy, exaggerates the 

 part played by the acidity of citrus fruits in protecting them from C. capitata attack. 

 In Hawaii his conclusions have not been borne out by the results of investigations by 

 the writers. The data in Table VIII are presented in detail because of the difference 

 of opinion existing between investigators as to the cause of egg and larval mortality in 

 the citrus groups. The conclusions of the writers, based upon extensive examinations, 



1 Back, E. A., and Pemberton, C. E., Susceptibility of citrus fruits to the attack of the Mediterranean 

 fruit fly. Jour. Agr. Research, v. 3, no. 4, Jan. 15, 1915. 



