432 



Journal of Agricultural Research 



Vol. XV, No. 8 



in the case of the male, it lies at the tips of the antejinae over the first 

 two abdominal segments. When the adult parasite emerges, this exuvium 

 is carried about for a short time on the antenna of the male or the 

 ovipositor of the female. With the complex changes in the alimentary 

 canal, accompanying the formation of the pupa, the unvoided waste 

 and accumulated food which fills the larval midintestine is forced to 

 occupy a greatly reduced space. In the pupa, then, the midintestine 

 is found to be short, oval, and filled with a dark compressed pellet (fig. 

 1 6). This pellet is the meconium. No portion of it is voided at the 

 time of pupation or during the pupal period. In the mature pupa this 

 meconium occasionally may pass into the hind intestine just caudad of 

 the urinary tubes, but it never passes from the pupa. The pupa stage, 

 following a short prepupal period of from i to 2 days, may last from 6 to 

 lo days. The duration of the pupa stage varies at any time of year. 



The duration of the combined ^gg, larval, and pupal periods (Table' 

 III) is from i8^ days in midsummer to about 25 days in the coolest 

 months. This represents the shortest period elapsing from egg to egg, 

 for oviposition may occur on the day of emergence. This is a slightly 

 shorter average period than obtains in the life of the fruit fly. 



Table III. — Duration of the cotnbined egg, larval, and pupal stages of Diachasma tryoni 



and Optus humilis 



o This table does not include hibernating individuals. 



ADULT 



The adult extricates itself from the host puparium by actively gnaw- 

 ing the part directly in contact with the head. . In opening and closing 

 the mandibles a transverse cut is made, usually in the third or fourth 

 pupal segment and extending around about one-third of the circum- 



