246 



Journal New York Entomological Society. [Vol. xxii. 



Table I. 



Experiment. 



Vegetable oils 



Animal oils 



Naptha 

 distillate 



Burning oil 

 distillate 



Lubricating 

 distillate 



oil 



f Citronclla oil I 



J Turpentine HI and IV (average) 



I Cocoanut oil Ill and IV (average) 



r Whale oil I 



"[pish oil I 



r Distillate about 48° Be VIII 



Benzine about 58° Be. VII and IX (average) 



Gasoline about 63° Be VI 



Gasoline about 86° Be V and IX (average) 



'Export oil about 110° Be XI 



Star oil (kerosene) about 120° Be. XI 



Mineral seal oil XI 



Colza burning oil XI 



Perfection signal oil XI 



r Renown engine oil F. 375 XII 



J Atlantic red engine oil F. 350.. XII 

 Crude petroleum XIII 



Per 

 Cent. 



.04 



103 



82 

 61 



27 



34 

 100 



14 



6 



o 



68 



It is evident that the attraction of the Mediterranean fruit fly to 

 these oils was confined ahnost entirely to the male sex. Female flies 

 were present in these orchards because hundreds were caught by 

 sweeping with an insect net among the fruit trees. Trapping the 

 pest with kerosene was carried on for a period of eight months in the 

 Hawaiian Islands in connection with other experiments and the results 

 show that of every 1000 fruit flies captured only 3 on an average 

 were females, the remainder being males. ■ 



Why should enormous numbers of male fruit flics and only a few 

 females be captured in certain oils? Concerning the behavior of 

 Dacus zonatiis towards citronella oil. Howlett (1912, ]). 413) writes: 

 " Since the reaction was confined to the male sex and did not appear 

 to be in any way connected with feeding habits, it seemed most reason- 

 able to suppose that the smell might resemble some sexual odor of the 

 female which in natural conditions served to guide the male to her." 

 This is, in substance, a view which we also expressed to a number of 

 entomologists and mentioned in a paper read before the Agricultural 

 Seminar in Honolulu on January 1 1, 1912, to explain the behavior of 

 the male Mediterranean fruit fly towards kerosene. Howlett believes 

 that " the smell is in all probability perceived by means of tlie 



