THE MELON FLY. 27 



during the winter, but feed continuously throughout this period, it 

 is evident that any spray that will kill them before they begin to lay 

 eggs is valuable. A poisoned-bait spray^ containing 5 ounces of lead 

 arsenate in paste form, 2-| pounds of brown sugar, and 5 gallons 

 of water, is very effective in killing adults. This spray, used at the 

 rate of 30 gallons to the acre, was applied by means of a knapsack 

 sprayer. About 2 acres of Chinese melons and cucumbers in a field 

 fairly well isolated, from the Hawaiian standpoint, which means 

 that no host fruits were growing within 500 yards, were sprayed on 

 May 21, 26, and 28j June 1, 4, 8, 14, and 23 during typical summer 

 weather. Six hours after an application many adults were sluggish 

 and flew with difficulty, but within 24 hours many dead adults could 

 be found among the vines. Although the adults were lessened nu- 

 merically by the spray, the young fruits were punctured as badly at 

 the end of the experiment as at the beginning. 



Although negative results have followed the use of poisoned-bait 

 sprays in Hawaii, failure has been due to the peculiar conditions sur- 

 rounding the fields sprayed that permit an influx of female flies. 

 Under commercial conditions, where cantaloupes, pumpkins, and 

 watermelons are grown in large quantities in fairly dry climates, it is 

 reasonable to believe that sufficiently good results will follow the 

 use of poisoned sprays to make their application practicable as a 

 method of control. 



DESTRUCTION OF INFESTED FRUITS. 



Larvse and eggs may be killed by submerging the infested por- 

 tions of the plant in water, or by burying, boiling, or burning. Choice 

 of method will depend largely upon the amount of fruit to be 

 handled and upon local conditions. There is no surer way to kill all 

 immature stages than to boil or burn the fruits. Burning is often 

 expensive, and, when trash in compost holes is depended upon to 

 furnish the fuel, is likely to be unsatisfactory, particularly where, as 

 in Honolulu, the quantity of infested material is so great. Bringing 

 infested fruits to the boiling point will kill all forms. The sub- 

 merging of fruits in ordinary tap water for five days will either 

 kill all larvae and eggs or stop further development. 



Burial in soil is a satisfactory method, provided the fruits are 

 buried deep enough and cracks are prevented from developing in 

 the earth above the fruits as the latter decay and settle. It must 

 be remembered that just after transforming from the pupa the 

 adults are so soft that they can force their way through very small 

 openings. A crack in the soil extending down to the fruit, even 

 though it be no wider than ordinary blotting paper, is still wide 

 enough to allow the adults to reach the surface and thwart the pur- 

 pose of fruit, burial. Adults can not make their way through a foot 



