10 BULLETIN 1081, U. S. DEPARTMENT 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 
23oisons, 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 compounds 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 production of 
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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