10 BULLETIN 1081, u. s. departme:nt of agriculture. 



as the plain sirup. Very good killing results were also obtained 

 by spraying this mixture with an atomizer on the under sides of the 

 leaves of the trees in the large cages. Large numbers of flies were 

 found dead on the ground within a couple of hours. These soluble 

 poisons, however, burn the trees very severely and can not safely be 

 used. Even at the rate of 1 pound to 50 gallons, which is as weak 

 as can be effectively used, severe injury was noted. Insoluble ar- 

 senic comjDounds such as Paris green, arsenate of lead, arsenate of 

 calcium, and arsenite of zinc do not damage the trees but are not 

 effective. When the arsenic is mixed in the sirup the flies do not 

 get enough to kill them. 



The following plan if carried out thoroughly will very materially 

 reduce the number of flies and make the growing of- papayas prac- 

 tical and profitable: (1) Selection of good seed and prodaction o^ 

 fruits of oblong shape and thick flesh which will offer more or less 

 immunity to attack; (2) conscientious destruction of the infested 

 fruits on the trees early in the season and before the maggots escape 

 into the ground; (3) destruction of all inferior plants and wild 

 plants around the place which might serve to breed the pests. 



If a planting is sufficiently isolated from other papayas the flies 

 may be killed out by destroying all the plants in the spring, about 

 April or May, and resetting new plants. These young plants will 

 begin to fruit in the summer or early fall, but there will be a period 

 of about 60 days when no fruits are present, which is long enough 

 to starve out the flies. Along with this program should go the 

 destruction of all wild plants in the hammocks for a radius of at 

 least 2 miles. One large planting under observation was kept free 

 from infestation for the entire winter by this method and a good 

 crop of fruit obtained. The previous winter and spring the plants 

 were badly infested, but the pests were entirely starved out during 

 the summer. In most locations, however, a grower would not be 

 sufficiently isolated to practice this method successfully unless the 

 cooperation of his neighbors could be enlisted. 



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