Jan.. 15 191S Citrous Fruits and Mediterranean Fruit Fly 325 



when the monthly mean temperature normally ranges from 62.5° to 

 64.8° F., the senior writer, with the kind assistance of Mr. E. J. Wortley, 

 Director of Agriculture, Bermuda Agricultural Station, found that the 

 length of the pupal stage was about 31 days, which would make the 

 period for development from egg to adult about 58 days in favored 

 hosts. In Honolulu the cold-storage experiments of the writers have 

 shown that the fruit fly requires about 91 days to complete the same 

 development at about 56° F. A temperature of 54° to 57° will not 

 prevent adults from emerging from pupae in cold storage, although it 

 lengthens the pupal stage from 8 days, a normal minimum required at 

 Honolulu in warm weather, to 36 days. Very few eggs out of several 

 hundred were able to hatch at a temperature of about 53° to 54°, while 

 practically no eggs will hatch nor larvae mature at a temperature of 

 50° F. A continued temperature ranging from 33° to 46° F. will kill 

 pupa; and larvae, although both may be subjected to these temperatures 

 for short periods without apparent injury. Freezing temperatures 

 have proved generally fatal to both larvae and pupae. At 45° larvae are 

 not able to pupate, although some hardy specimens may become active 

 and pupate if removed at the end of a month from this temperature to 

 the normal Honolulu summer temperature. A total of 10,203 second 

 and third instar larvaa kept at a temperature varying from 42° to 46° 

 were all dead at the end of 45 days, except one third-instar larva which 

 was probably moribund, while out of 10,959 second and third instar 

 larvae kept at a temperature varying from 33° to 38° none were aUve 

 after the seventeenth day. 



These data from the notes on file are given here to show that even the 

 cool winter climate of the lowlands of Hawaii has a decided effect in 

 checking the increase of the fruit fly, that temperatures as low as 56° F. 

 greatly lengthen the life cycle, and that a temperature of 50° to 52° 

 practically prevents eggs from hatching. Unfortunately no data are at 

 hand on the effect of the temperature varying above and below a mean 

 temperature ranging from 50° to 53°. Certain deductions, however, 

 can be made from known facts regarding the development of the fruit 

 fly in the Mediterranean region, especially in southern Spain, France, 

 Italy, and Sicily, that show that the fly does not multiply, or at least 

 undergoes an extremely slow development, -when the monthly mean 

 temperatures range from 50° to 54°. During the spring and summer 

 of 1913, Prof.'H. J. Quayle, of the University of California, investigated 

 the status of the fruit fly in the Mediterranean regions for the Bureau of 

 Entomology,' and his observations bore out the contentions of the 

 present Italian entomologists that the fruit fly is not a serious pest to 

 Citrus in Spain and Italy. The fact that Prof. Quayle found no evidence 



* Quayle, H. J. Citrus fruit insects in Mediterranean countries. U. S. Dcpt. Act.. Bui. 134. 33 p.. 2 fig.. 

 10 pi. 1914. 



