4 BULLETIX 1081, JJ. S. DEPARTMEjSTT OF AGRICULTURE. 



attempt to i^upate. but many of them die before completing the trans- 

 formation. Even when thej' 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 puparia 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 imder 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, subcylindrical 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 pujDal 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 

 temj)erature changes the eifect 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 ' found it to last from 17 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 TO 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. 



