Sept. 21, 1914 
Papaya Fruit Fly 
45i 
unripe fruit. These dead larvae are always full grown and therefore 
perished at the time that they would have normally made their 
escape from the fruit, in order to pupate in the ground. In ripe fruit 
mature larvae are easily able to bore out through the soft meat, which 
then no longer exudes the gummy juice characteristic of unripe fruit; but 
the sticky exudation of the flesh and rind of unripe fruit is fatal to the 
larvae, probably by asphyxiation. 
PUPAL PERIOD 
The larvae, when about to pupate, usually leave the fruit as just 
described and fall to the ground. The pupal period is passed either 
under some fragment of coral rock or in the soil at a depth of 1 or, 
at the most, 2 inches below the surface. Rarely puparia were found 
within the hanging fruit. The pupal period varies according to the 
meteorological conditions. In Porto Rico, Hooker (1913), found that 
the duration of the pupal period was from 17 to 21 days. The observa¬ 
tions of the authors, made in the cool season of the year, showed a pupal 
period of from 30 to 42 days. They further show that moisture condi¬ 
tions, as well as those of temperature, affect the length of the pupal 
period, and that excessive dryness has a retarding effect and if prolonged 
may prove fatal. 
HABITS OF THE ADULT FLY AND OVIPOSITION 
Special effort was made to learn something of the habits of the adult 
fly. The senior author, while at Miami, made frequent visits to the 
papaya plantation at the Subtropical Plant Introduction Field Station 
and to the hammock south of it, with this object in view. Careful watch¬ 
ing in the vicinity of the papaya plants, and vigorous searches were alike 
unsuccessful until near the close of the investigation. It was then found 
that the flies are only active for a very short period just before sunset. 
About half an hour before sunset a female papaya fruit fly came with 
rapid flight and alighted unhesitatingly upon a well-developed but green 
papaya. After walking about a little on the top of the fruit, the fly began 
to insert its long ovipositor, and in a remarkably short time had sunk it 
full length into the fruit. As soon as the fruit was punctured the milklike 
liquid, which the unripe fruit exudes wherever injured, welled forth and 
began to trickle down the side. The fly very soon withdrew its ovipositor 
and was about to take wing when it was captured. In the course of 
about 15 minutes some eight or more flies were seen, all behaving in 
the manner described, and four of these were captured in the act of 
puncturing the fruit. The next evening, in the same place, a few more 
female flies were seen at about the same time, but none earlier and none 
later. It seems evident that flight and oviposition occur at a definite 
time in the evening, a little before sunset, and are governed by the 
amount of light. Under the conditions observed, viz, on bright, nearly 
cloudless days, this activity does not last more than 15 or 20 minutes. 
There may also be a morning flight, for Mr. Simmonds stated that he had 
captured the fly early in the morning. 
It is evident that the female endeavors to thrust her ovipositor through 
the meat of the fruit to deposit her eggs in the central seed chamber, 
and it is only in the varieties with thinner meat that she can succeed. 
With the exception of mature larvae in ripe fruit, the larvae are always 
found within the seed mass. It is only when they are full grown, or 
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