THE MELON FLY IN HAWAII, 49 



tween June 14 and 23 was sufficient to permit an accumulation of 

 adults equal to that at the beginning of the experiment. Six hours 

 after an application no dead flies could be found, though many were 

 sluggish and flew with difficulty, Twenty-four hours after an appli- 

 cation many flies could be found dead among the vines. While the 

 adults were lessened numerically, the young fruits were as badly 

 punctured at the end of the experiment as at the beginning. Dr. 

 Illingsworth, of the College of Hawaii, has had only negative results 

 in his experiments to save cucurbit crops by spraying, although he 

 has been able to kill large numbers of adults. 



While the writers have had negative results with poisoned-bait 

 sprays, they feel that their failure has been due to peculiar conditions 

 surrounding the fields sprayed. Under commercial conditions, where 

 cantaloupes, pumpkins, and watermelons are grown in large quanti- 

 ties in fairly dry climates, it is reasonable to believe that sufficiently 

 good results will follow the use of poisoned sprays to make their ap- 

 plication practicable as a method of control. In Hawaii the grow- 

 ing of these crops is in the hands of Orientals, who do not appreciate 

 the necessity for clean cultural methods as an adjunct to spraying. 

 Their gardens, scattered here and there, form excellent breeding 

 places and centers of distribution. These conditions, coupled with 

 the very long life of the adult and its roving disposition, make it im- 

 possible to protect small fields of host plants in Hawaii at the present 

 time by spraying, particularly during the warm season of the year. 



Cold storage. — The only data on the effect of cold-storage tem- 

 peratures upon the immature stages of the melon fly are those in- 

 cluded in Tables VIII and IX. Fewer experiments have been car- 

 ried on by the writers to determine the effect of cold-storage tem- 

 peratures upon the melon fly than upon the Mediterranean fruit 

 fly, since it has been found that the stages of the former are not more 

 resistant. Consequently host fruits refrigerated for periods suffi- 

 ciently long to kill the Mediterranean fruit-fly eggs, larvae, and 

 pupae are free from danger as carriers of the melon fly; i. e., if re- 

 frigerated at from 40° to 45° F. for 7 weeks; from 33° to 40° F. for 3 

 weeks; or from 32° to 33° F. for 2 weeks when the humidity ranges 

 between 80 and 91. A comparison of the data in Tables VIII and 

 IX with those already published on cold-storage effects upon the 

 immature stages of the Mediterranean fruit fly indicates that the 

 eggs and larvae of the melon fly and Mediterranean fruit fly are 

 about equally resistant to cold-storage temperature, but that the 

 pupae of the melon fly are much more susceptible. While no pupae 

 of the melon fly survived refrigeration at from 32° to 33° F. or from 

 34° to 36° F. for 5 days, or from 36° to 45° F. (averaging 38° F.) for 

 9 days, pupae of the Mediterranean fruit fly were not found to be 

 65732°— Bull. 491—17 -4 



