MEDITERRANEAN FRUIT FLY IN HAWAII. 17 



oranges may be quite thoroughly devoured within and yet maintain 

 a fairly normal appearance externally. In rapidly growing fruits, 

 or those oviposited in while they are still too green to support larval 

 growth, slight deformities are developed which injure the appearance 

 of the fruit. In lemons, oranges, and grapefruit which have been 

 provided so well by nature to withstand fruit-fly attack, the rind may 

 become badly infested with eggs and young larvae, while the pulp 

 remains edible. The breaks in the skin made by the female fly in de- 

 positing eggs, however, affect the shipping qualities of such citrus fruits 

 and, from this commercial aspect, may cause an injury the nature of 

 which is quite as serious as is any to the pulp. 



EXTERNAL EVIDENCES OF INJURY. 



There are always external evidences of infestation, but these are 

 often so inconspicuous that they are overlooked by the average 

 person. The eggs are deposited by the adult through a break, no 

 larger than a pin prick, made in the skin. While these punctures 

 are readily discernible under the hand lens as soon as made, there is 

 nothing about them to attract attention. Soon after oviposition, 

 however, the tissues about the egg cavity begin to wither and 

 there develops about the puncture a discolored or sunken area in the 

 skin. In certain hosts the immediate area about the puncture may 

 remain green long after the remainder of the fruit has turned yellow, 

 as in the loquat (Eriobotrya japonica), or red, as in the strawberry 

 guava (Psidium catileyanum) . In green oranges the fruit may turn 

 yellow about the puncture while the rest of the fruit remains green. 

 Such tender-fleshed fruits as the ripening Surinam cherry (Eugenia 

 michelii) may develop sunken areas without discolorations. Often 

 filaments of clear gummy excretions exude from punctures made in 

 peaches, lemons, and grapefruit. Punctures made in green star 

 apples (CJirysophyllum cainito) are usually marked by exuding white 

 latex which dries about and over the puncture. Punctures made in 

 quite green winged kamani nuts (Terminalia catappa), in which no de- 

 velopment of larvae occurs, are marked by depressions in the flesh due 

 to permanently arrested development at the punctured point. 

 Oviposition or attempted oviposition in bananas and partially ripe 

 mangoes is followed by exudations which run down the sides of the 

 fruit and dry as a dark stain. The evidences of early infestation 

 such as have just been mentioned are too numerous to warrant de- 

 scription. No one host responds to infestation exactly the same 

 each time; much depends on the degree of ripeness at the time of 

 attack. There may be no gummy exudations from peaches or citrus 

 fruits, and there may be no development of discolored areas in any 

 of the host fruits. Avocados seldom give evidence of infestation by 

 any external mark except the puncture in the skin. Fruits already 

 81340°— 18— Bull. 536 2 



