324 J ourncd of Agriculhiral Research voi. ni.xo. 4 



SECONDARY ATTACK OF CITROUS FRUITS BY INSECTS OTHER THAN 

 THE FRUIT FLY AND BY FUNGI 



The excellent experimental work of the Bureau of Plant Industry 

 carried on in Florida during the last few years has forcibly demonstrated 

 the causes of decay of citrous fruits in transit from orchard to market. 

 Mechanical injuries to the rind have been found to be a fertile source 

 of trouble by furnishing entry for decay fungi. The writers believe 

 that a great share of the decay of oranges en route to market, recorded 

 in the early history of the Mediterranean fnut fly, was caused more by 

 insanitary conditions in the holds of ships than directly by fniit-fly 

 larvae. It is more than likely that the oranges shipped from the Madeira 

 Islands and the Azores to London contained fruit-fly punctures which 

 greatly aided the blue mold in its destructive work. 



Statements made by the early writers and even repeated in the 

 Hawaiian Islands at the present time, that citrous fruits drop as soon 

 as punctured, are untrue. There is no such thing as a general shed- 

 ding of fruits following puncturing of the rind. Oranges and grape- 

 fruit have been known by the writers to hang on the tree from two to 

 three months after they were first punctured. It is probable that the 

 wholesale shedding of fruit recorded by others was caused by fungi or 

 physiological troubles. 



Species of Drosophila and Bruchus may usually be found ovipositing 

 in breaks in the rind of Citrus made by the Mediterranean fruit fly. 

 Their persistent attack, supplemented by decay fungi, causes an appre- 

 ciable amount of decay in Hawaii. 



EFFECT OF ATTACK OF THE MEDITERRANEAN FRUIT FLY UPON 

 CITROUS CROPS OF CALIFORNIA AND FLORIDA 



In the opening paragraph the writers made the statement that their 

 investigations in Hawaii have led them to believe that even if the Mediter- 

 ranean fruit fly should be introduced into the citrous regions of the 

 United States it would not become a serious pest to citrous fruits. In 

 the Hawaiian Islands, especially in the lowlands, climatic conditions are 

 more favorable for the rapid increase of the fruit fly than they are in 

 any section of the United States or of the Mediterranean regions where 

 oranges are grown commercially. The monthly mean temperatures at 

 Honolulu during 1912 and 1913 ranged from 69.6° to 79.2° F. During 

 the hottest summer weather the fniit fly requires a minimum of about 

 14K days to complete its life cycle from egg to adult. During late 

 December, 1913, and January and early February, 1914, it required 

 many flies fully 47 days to reach maturity in common guavas {Psidium 

 guajava). During March and April, 1914, the fruit fly required from 

 20 to 30 days to pass from egg to adult in half-ripe peaches and from 28 

 to 40 days in lemons. In Bermuda during December and January, 



