450 
Journal of Agricultural Research 
Vol. II, No. 6 
THE PUPARIUM 
Puparium (PI. XLII, fig. 3) of the usual stout subcylindrical form, with rounded 
ends; slightly depressed ventrally, the larval callosities obsolete; laterally with a 
series of shallow longitudinal impressions; stigmatal area hardly differentiated; anal 
papillae prominent; color ferruginous yellow to light ferruginous. 
HABITS OF THE LARVAE 
The papaya fruit-fly larvae occur in the interior of the fruit, first feed¬ 
ing in the central seed mass, but later, as they mature and the fruit 
ripens, working into the meat and ruining the fruit (PI. XLII, fig. 4). 
The number of larvae in a single fruit varies from 2 or 3 to 20 or more. 
Sometimes larvae of different sizes occur within the same fruit, showing 
that the infestation was from more than one oviposition. 
The cultivated fruit in the Subtropical Field Station at Miami was 
by no means so generally infested as the wild fruit in the hammock 
south of it. Evidently infestation stood in relation to the thickness of 
the meat of the fruit, in that cultivated forms having the thickest meat 
were least affected. Several of the latter, some still small and others 
nearly ripe, were cut open, and no maggots could be found. The only 
evidences of injury to these thick-meated fruits were numerous scars 
that had the appearance of egg punctures. On the other hand, the fruit 
of volunteer plants in the Field Station, with thin meat and large seed 
cavity, was frequently infested. 
The wild fruit in the hammock 1 was found to be very badly infested 
with papaya fruit-fly larvae. This wild fruit is very small and seldom 
exceeds 2 inches in diameter. The meat is thin, and there is compara¬ 
tively little flow of juice when the surface is injured. 
To determine the amount of infestation in the wild fruits of different 
sizes or ages, an examination was made of small fruits about three- 
fourths of an inch in diameter, medium-sized fruits, and large ripe fruits. 
Out of 208 small fruits, 41 showed infestation, and 167, or 80 per cent, 
were sound. Out of 52 medium-sized fruits 26, or 50 per cent, were free 
from infestation. Examination of 25 nearly ripe fruits showed that 
none were sound. Again, in a miscellaneous lot of 63 fruits, 32, or over 
50 per cent, were infested. In general, small or young fruit is much less 
infested than the older fruit, the flies evidently selecting the larger and 
more mature fruits for oviposition. 
A remarkable fact was the occurrence of dead full-grown larvae in 
fruits externally sound. In the 208 small fruits, 33 living and 3 dead 
larvae were found. In the 52 medium-sized fruits there were 22 living 
larvae and 1 dead larva. In the miscellaneous lot of 63 fruits there 
were 82 living larvae and 38 dead ones. In the 25 nearly ripe fruits, 
however, the dead larvae exceeded the living ones, there being 12 of the 
former and 6 of the latter. The importance of these data will be dis¬ 
cussed farther on. 
It was found that contact with the juice of the unripe fruit is quickly 
fatal to the larvae, which explains the presence of the dead larvae in 
1 In the hammock, the virgin tropical vegetation to the south of Miami, papaya plants were growing 
adventitiously in large numbers, particularly along the edges of the hammock and in the more open spots. 
The abundance of these wild papayas was traceable to the operations of real-estate men, who, about a year 
earlier, cleared the trees and shrubs from a portion of the hammock to lay out streets. In these cleared 
places the papaya had sprung up in great profusion. On the authority of Mr. W. E. Safford, of the Bureau 
of Plant Industry, wherever the papaya is grown wild plants very quickly spring up adventitiously in 
the vicinity, particularly in newly cleared land. Undoubtedly the seeds are distributed through the 
agency of birds, and in this way the plants make their appearance at a distance from the point of cultivation. 
