474 THE SMALL GRAINS 



develop to flaxseeds before harvest, and pass the summer 

 in the stubble. From these arise the second generation 

 of adults, which deposit their eggs on the new fall-sown 

 wheat, when there is a repetition of what has just been 

 described. Flies from the over-wintering larvae appear 

 later. These, with probable other adults resulting from 

 eggs deposited earlier in the spring, form sometimes just 

 before harvest what is called by some a supplementary 

 second generation. In autumn the time of appearance of 

 adults as between North and South is reversed from that 

 in the spring. In the North they appear much sooner, 

 during the last of August and first of September in north- 

 ern Michigan. In Georgia and South Carolina it may be 

 the last of November or first of December before they all 

 leave the stubble. Here again the earliest deposited eggs 

 may be able, because of the long autumn, to produce 

 adults before cold weather, which with the delayed indi- 

 viduals of the preceding generation form another so-called 

 supplementary generation. 



In the northern spring wheat districts the insect winters 

 in the flaxseed stage in both stubble and volunteer wheat, 

 but chiefly in stubble. Eggs are laid late in May, and 

 in rainy seasons the second generation quickly follows, 

 to which are added flies still continually emerging from 

 the previous year's stubble. The breeding season extends 

 from about May 20 to October 1, or practically the entire 

 summer. 



519. Effect of the larvae on cereal plants. Soon after 

 the larvse pass down from the leaf on to the straw inside 

 the sheath, they produce a marked effect upon the plant. 

 The uninfested wheat plant is of slender growth, has a 

 light green color tinged slightly with yellow, the stems are 

 usually visible, and the central unfolding leaf is present, 



