380 Journal of Agricultural Research voi. vi, no. 10 



their growth remained in a quiescent state in the little glass cells for 

 months. Others pupated at once upon completing their growth. 



THE PUPA 



In general, the process of pupation as observed in glass cells is as follows : 

 The full-grown larva excretes all waste matter from the body, leaving it 

 perfectly white. Within a day after this operation the pupa (PI. LI, 

 fig. 8) is formed and is at first perfectly white, the last larval skin being 

 found at the anal end of the pupa. In another day or so the pupa begins 

 to turn a pale brown, and the eyes turn reddish. The pupa finally 

 becomes entirely black as development progresses, the head and thorax 

 changing first, and remains so until the adult emerges. 



The pupa is formed naked inside the puparium of the host. The adult 

 emerges by casting off the pupal skin inside the host puparium and then 

 cutting a round hole through the side of the flaxseed near one end. The 

 length of the pupal period varied in 21 instances from 7 to 13 days. Cool 

 weather retarded the development of the pupae. A larger proportion of 

 the larvae reared in the cooler weather of fall pupated at once upon attain- 

 ing their growth than was the case with the larvae reared in the hot 

 weather of midsummer, indicating a tendency of the larvae of this species 

 to estivate. 



THE ADULT 



Newly emerged adults became active almost at once upon emerging 

 from the host puparium. Males placed in the same cage with females 

 began mating at once. Females that had been mated seemed to oviposit 

 more readily than unmated females. Both Mr. McConnell and the writer 

 found that this species was arrhenotokous in every instance where this 

 point v/as determined. Females have been kept alive in cages as long 

 as six months, and one female oviposited after having been kept alive 

 over five months. It was usual for them to live and oviposit for at least 

 a month in vial cages. One female actively oviposited during a period of 

 75 days and laid a total of 103 eggs. Another female laid a total of 45 

 eggs. The number of eggs laid by a single female was determined by 

 exposing flaxseeds to an isolated individual and dissecting them to find 

 the number of eggs the parasite had laid in each. 



In ovipositing the female would run up and down the stems of the 

 plants, vibrating her antennae against the surface. When she came to a 

 place in the stem where a flaxseed was located, she would stop, feel up 

 and down over the spot with her antennae, and then lower the tip of her 

 abdomen. When she had found the point that suited her for oviposition, 

 the end of the abdomen was raised, leaving the ovipositor standing 

 vertically against the side of the stem from its articulation with the 

 middle of the abdomen. In penetrating the leaf sheath and puparium 

 the parasite seemed to rotate the ovipositor with a drilling motion in 



