MEDITERRANEAN FRUIT FLY IN HAWAII. 115 



emergence from these pupae is given in Table XXXII. The data 

 covering lots 1 to 6 show that the more mature pupae succumbed to 

 immersion more quickly than the younger pupae of lots 7 to 12. Thus 

 many of the young pupae emerged as adults after being submerged 

 4, 5, and 6 days, while submergence for these periods killed nearly 

 all the older pupae. Submergence for at least 7 days is necessary to 

 assure the death of all pupae. 



BURIAL IN SOIL. 



Many entomologists have made statements regarding the efficacy 

 of burying infested fruits in the soil as a method of destroying fruit 

 flies. These references have been summarized by Severin, hence 

 need not be considered at length here, particularly as they deal with 

 a method that is decidedly unsatisfactory and seldom effective. 

 Gurney found that pupae buried 6, 8, and 12 inches below the surface 

 of the soil produced adults that were able to escape. Severin found 

 that adults could make their way to the surface from pupae buried 

 2, 3, and 4 feet beneath dry sand, and from pupae buried 2 feet beneath 

 wet sand, but that no adults escaped through 2, 3, or 4 feet of dry 

 soil. Mally found that 10 inches of soil shoveled loosely over fruits 

 did not prevent adults from escaping later, but that no adults could 

 reach the surface through 10 inches of well-tamped soil. No adults 

 escaped from 20 pupae placed in the center of a cake of mud one-half 

 inch square taken from the heavy, tenacious soil of the vegetable 

 gardens at Waikiki. The mud became thoroughly dry without 

 cracks before the end of the normal pupa stage. A cake of the same 

 soil 1-| inches square, however, on drying developed a crack through 

 which 50 adults made their escape from 75 pupae buried within the 

 center of the square. While adults can not make their way through 

 a foot of well-tamped soil, it is difficult to bury host fruits in such a 

 manner that the soil covering will remain firm. The rapid decay and 

 settling of fruit, if any amount be buried in the same excavation, 

 cause cracks to develop through which adults can escape readily. 

 While many fruit flies can be killed by proper burial, indifference and 

 carelessness among workmen will always make possible the escape 

 of many adults. 



BURNING AND BOILING HOST FRUITS. 



Burning or boiling host fruits is a sure method of destroying the 

 immature stages of the Mediterranean fruit fly provided the work 

 is feasible and can be done thoroughly. The usual practice of throw- 

 ing fallen infested fruits into a compost pit and burning over them 

 every few days such trash as may have accumulated is not a trust- 

 worthy method of destruction, inasmuch as the heat produced is 

 very often insufficient to cook or burn the fruit thoroughly or to reach 

 the pupae in the soil beneath the fruit- 



