3 7^ Journal of Agricultural Research voi. vi. No. lo 



have hibernated in stubble of wheat cut the previous June. Eight per cent 

 of the flaxseeds in stubble gathered from a field in southeastern Kansas 

 in late March contained live, full-grown parasite larvae which afterwards 

 became adult and were determined by Mr. Gahan as M. dcstrtictor. 



THE PUPA 



The period from the formation of the pupa (PI. "LI, fig. 6) to the emer- 

 gence of the adult varied from 7 to 14 days in 2 1 specimens carried through 

 this stage in glass cells. Those pupating in April and September, when 

 cooler temperatures prevailed, took longer to develop than those which 

 pupated during the hot weather of July and August. The larvae form 

 naked pupae inside the puparium of the host. The process of pupation as 

 observed in glass cells begins with the excretion of all waste matter 

 from the body of the larva, which then becomes pure white. In a few 

 hours the pupa is formed. The eyes begin to turn reddish in about a 

 day and by the fourth day are a very dark red. The body of the pupa 

 is by the fourth day a creamy white, and by the sixth day the head 

 and thorax are black. Within another day the abdomen turns black 

 except for the base of the abdomen, which assumes the light brown as 

 found in males and some females. The emergence of the adult follows 

 vdthin a day or so after the pupa has turned dark. Cool weather retards 

 development. The adult casts off the pupal skin inside the host puparium 

 and emerges by gnawing a round hole through the side of the flaxseed 

 and the wheat leaf sheath covering it just large enough for the adult para- 

 site to crawl through. 



THE ADULT 



Adults soon become active after emerging from flaxseeds. In the 

 spring males emerged two or three days before the females in cages con- 

 taining stubble collected from the fields where it had stood during the 

 winter. Mating took place at once when the females emerged. Oviposi- 

 tion takes place in the following manner : The females run up and down the 

 wheat stalks, vibrating their antennae rapidly against the side of the stem. 

 When they come to a place where there is a flaxseed underneath the leaf 

 sheath, they stop and excitedly feel up and down over the place where 

 the flaxseed is located. They face upward to oviposit, with the body 

 parallel to the puparium. They locate the proper place for oviposition 

 with the tip of the abdomen and then raise it away from the stem, leaving 

 the ovipositor unsheathed and pointing perpendicularly against the stem 

 from its articulation with the middle of the abdomen. In less than a 

 minute the ovipositor is forced through the leaf sheath and the puparium. 

 In penetrating the flaxseed the ovipositor is seemingly rotated like a drill 

 part way round and back again. Oviposition takes 5 to 10 minutes, and 

 dissections of flaxseeds indicate that a single egg is laid at a time. One 

 female kept isolated in a vial cage laid a total of 39 eggs in puparia exposed 



