4 BULLETIN 1081, U. S. DEPARTMENT OF AGRICULTURE. 
attempt to pupate, but many of them die before completing the trans- 
formation. Even when they succeeded in pupating, the adults never 
matured from them. Evidently this is due to a lack of moisture, 
which seems to be a vital factor to all stages of development in this 
insect. 
PUPARIUM. 
In common with other fruit flies, this insect passes the pupal stage 
in the ground. The pup aria occur naturally under the infested 
trees in the soil. for. as stated above, the maggots do not travel 
around, but go into the ground where they fall. The average depth 
of the puparia is 2 inches, although they vary anywhere from the 
surface to 3 inches deep, and sometimes occur also under rock and 
rubbish on the surface. The moisture in the earth seems to deter- 
mine largely this point, for they go down until they can get into 
damp soil. Very rarely one is found inside the fruit either on the 
tree or on the ground. 
The puparia (PL I, B) are of a stout, subcylindrieal form with 
rounded ends and vary in length from 8.5 to 12 mm. The size is no in- 
dication of sex, for from 100 of the smallest ones obtainable about 
an equal number of males and females emerged. The color of the 
puparia varies all the way from a light ferruginous yellow to dark 
brown or almost black. This color in no way indicates their age. 
for some remain light colored throughout their existence. 
The pupal stage was found to vary from 18 to 44 days in breed- 
ing out several hundred in all months of the year. Aside from the 
temperature changes the effect of the moisture is a very large factor 
in this regard. Under favorable conditions of moisture the largest 
number of the adults will emerge after 18 to 20 days in hot weather, 
but in winter this runs up between 30 and 40 days on the average. 
Hooker 4 found it to last from IT to 21 days in Porto Rico. Mois- 
ture, even more than heat, seems to be the determining factor. Lack 
of moisture will prolong very materially the pupal stage and if con- 
tinued will prove fatal. On the other hand, excessive moisture will 
kill the puparia. The following data prove this point : 
One hundred fresh puparia placed in soil in a jar and kept without any 
water being added. All died. 
One hundred fresh puparia placed in soil in a jar and kept moderately moist ; 
80 adults emerged, 20 died. 
One hundred fresh puparia placed in soil in a jar and kept wet every day. 
All died. 
Even under the most favorable conditions of heat and moisture 
the puparia do not all mature, and 70 per cent is a very good aver- 
age. Under natural conditions the average runs below that. Sev- 
* Hooker, C. W. Fruit flies. In Porto Rico Agr. Exp. Sta. Ann. Rpt. 1912. p. 36. 1913. 
