45 2 
Journal of Agricultural Research 
Vol. II, No. 6 
nearly so, that they enter the meat, work their way out, and drop to the 
ground, in order to pupate just beneath the soil. As already pointed 
out, the juice from the injured meat of the unripe fruit is fatal to 
the larvae; therefore the eggs must be placed beyond it in the seed 
chamber. 
Later observations were made by Mr. C. A. Mosier, of Little River, 
Fla., who has had many opportunities to observe the papaya fruit fly. 
He recently forwarded the following notes on its habits: 
The flies do not oviposit on very young fruit, but are found more on large to full- 
grown fruit. One female was captured with the ovipositor fully embedded in three- 
fourths ripe fruit. I also noted that the flies skipped deformed and gnarled fruit. 
More females are out on dark cloudy days, while the males are active and predominate 
on warm sunny days and are sluggish on dull days. 
Also, I have found three females dead, or nearly so, that had been trapped by the 
juice of the fruit coagulating before the ovipositor was withdrawn. 
PAPAYA FRUIT FLY RESTRICTED TO THE PAPAYA 
The fact that in a fruit-growing section like southern Florida no com¬ 
plaints of infestation of fruits other than the papaya had been made 
was in itself evidence that the pest is peculiar to this fruit. This was 
confirmed by examination of other fruits and by transfer experiments. 
Immature larvae transferred to citrous fruits failed to complete their 
transformation and died. 
RAPID INCREASE OF THE FRUIT FLY 
During the last two years, more particularly as a result of the increased 
cultivation of the papaya in southern Florida, this fruit fly has also 
rapidly increased and extended its range so as to seriously threaten the 
future development of the papaya industry. Some varieties of Philippine 
stock producing large fruit grown at Lemon City, Fla., are apparently 
free from attack. A very fine large variety of fruit grown at Lemon 
City, Fla., from Philippine stock was found to be free from the larvae. 
CONTROL 
It has been pointed out that fruit with very thick meat escapes infes¬ 
tation. While the papaya fruit fly attempts to oviposit on such fruit, 
the thickness of the meat prevents the tip of the ovipositor from reaching 
the seed cavity, and in the meat itself the larvae caii not live. It was 
further found that in some fruits the larvae had reached maturity before 
these had ripened and had been killed by the sticky juice of the green 
fruit in endeavoring to escape. The means of control that now seem 
valuable are the production of varieties of papaya that have thick meat 
and that ripen slowly, and the conscientious destruction of adventitious 
or wild papaya plants and of all infested fruits. All plants with inferior 
fruit should be eliminated. 
