MEDITERRANEAN FRUIT FLY IN HAWAII. 31 



the individual tree) that the eggs are laid either in the cavity in the rind, or between 

 the rind and pulp but directly beneath the puncture, suffer a degree of mortality 

 between that of eggs deposited in Chinese oranges and Kusaie limes. Mandarins and 

 tangerines in Hawaii usually are infested if allowed to ripen thoroughly upon the tree. 

 The Satsuma orange is a fruit that easily becomes infested because of the looseness of 

 the rind and lack of well-developed rag. 



22. Lemon. 



Because of the danger of introducing the Mediterranean fruit fly from the Mediter- 

 ranean regions in lemons, the importance of this fruit as a host has been thoroughly 

 investigated at the request of Mr. C. L. Marlatt, chairman of the Federal Horticultural 

 Board. The observations of Martelli and Savastano in Italy have led them to definite 

 statements as to the immunity of commercial lemons to C. capitata in Italy. H. J. 

 Quayle, who conducted an investigation during 1913 in the Mediterranean citrus 

 regions under the direction of the Federal Horticultural Board, found less than 15 

 lemons with infested pulp during a search of eight weeks throughout commercial 

 lemon orchards in Italy and Sicily. It is interesting to record that of the 15 fruits 

 containing larvae within the pulp, all had the appearance of having been injured, 

 either mechanically or by fungi, and in all but two instances they were found in an 

 overripe and overdeveloped condition on the ground beneath the trees. The two 

 fruits found infested while still attached to the tree were partly decayed on one side. 

 These instances of infestation recorded by Quayle, who is thoroughly competent to 

 judge from long experience with citrus in California, refute the argument that lemons 

 are too acid to support C. capitata larvae, although the small number of lemons found 

 infested, of the thousands examined during the eight-week period, strengthens the 

 argument set forth by the Italian entomologists, as well as by the writers, that lemons, 

 commercially grown and cured, will not support the fruit fly if they are not first 

 subjected to some mechanical or other injury while still attached to the tree. 



In Hawaii, where climatic and host conditions are so favorable to C. capitata activity 

 and where every host is subjected to the severest tests, the writers have never found 

 a lemon of either the commercial or the rough-skinned type showing infestation of the 

 pulp unless it had first received mechanical injuries. Although there are compara- 

 tively few lemon trees in Hawaii, those known to the writers have seldom been found 

 infested. By "infested" is meant, in this instance, an infestation by C. capitata 

 larvae in the pulp. Out of 235 well-grown and for the most part ripe lemons of the 

 commercial type, picked from the tree, only one eventually developed adults, three 

 in number, and this fruit when picked was partially decayed as the result of a thorn 

 prick. Out of 161 lemons of the same variety taken from the ground in a very much 

 overripe condition, only two developed larvae, 1 and 5, respectively. No larvae devel- 

 oped in 434 ripe, rough-skinned, but badly punctured lemons picked from the tree. One 

 partially decayed rough-skinned lemon picked from the ground produced 12 larvae. 

 These instances of infestation of the pulp, taking place in the field, are the only ones 

 which have come to the attention of the writers during the past four years in Hawaii. 



The recording of so small a number of lemons with larvae developing in their pulp 

 should not be interpreted as meaning that lemons are particularly free from attack in 

 Hawaii. The data of Table VIII prove that, in reality, lemons of the commercial 

 type grown in Hawaii are very attractive to adult C. capitata as host fruit. The many, 

 fruits listed above from Hawaii from which no adults were reared were as heavily 

 infested in the peel as those recorded in Table VIII. Particular attention is drawn to 

 this point since it is the contention of the writers that the immunity of lemons, other- 

 wise uninjured, is due not so much to the acidity of the pulp as it is to the impervious- 

 ness of the rag. It seems incredible that lemons heavily oviposited in should be able 

 to resist successfully infestation of their pulp, yet this is true. Examination of 5 

 lemons showed that 73 of 79 egg cavities or punctures had been made between the 



