DIPTEEA OR TRUE FLIES. 



221 



Anchor Processe9. 



Anclior process of Hessian 

 fly ; 2, of Wheat midge. (Or- 

 inerod.) 



leaf of the young wheat-plants in May ; the small white 

 maggots crawl down the leaf, and bury themselves in the 

 leaf-sheath, generally taking up their 

 position ahove the second node from 

 the ground. Here these little white 

 larvae feed upon the sap of the plant, 

 and turn to the curious " flax - seed " 

 stage, in which the larva remains in its 

 old skin, which has hardened to form 

 the puparium, and which resembles a 

 flax-seed in appearance. The larvae are 

 at times pale green, at others tinted with red. In these flax- 

 seeds the larva turns to a minute pale-brown pupa. These flax- 

 seeds may remain as such all the winter, or they may give 

 rise to a second brood of flies. This second brood hatches 

 out in September, long before our wheat is up, and thus have 

 to lay their eggs on other plants, such as couch and timothy 

 grass, pupating there in 

 the spring, and then 

 give rise to the May 

 brood. The presence of 

 this pest in a field is 

 very marked. The straw, 

 as soon as the ear be- 

 gins to develop, bends over above the second node, 

 looks as if weather-beaten, the grain being small, if 

 spoilt. In America the second brood lays its eggs on the 

 young winter wheat, the larvae living in the crown of 

 the plant just beneath the ground, and causing the leaves to 

 present an unhealthy dark and broad appearance, the central 

 leaf usually disappearing. It is this method of attack that is 

 the most severe, whole strips of wheat being entirely killed by 

 it ;, but for obvious reasons we cannot suffer from this form of 

 attack on our side of the Atlantic. The Hessian fly is most 

 prevalent in the eastern counties of England, but may be found 



Fig. 119. — Wing of Ckcidomyia. 



and 

 not 



