116 



DISEASES OF CROPS. 



deeply ploughed, so tkat the stubble may be buried ; or it 

 may be cultivated, or scarified and the stubble harrowed 

 together and carefully burnt " (Whitehead). (6) Farmers 

 should " destroy ' flax-seeds * found (after threshing in- 

 fested straw) in siftings or light grain." (7) In the 

 United States of America stubbles are burnt as they 

 stand. In some cases this method might be advantage- 

 ously applied in England. 



Cure. — (I) Dressings of gas-lime, in either the autumn 

 or spring, have been recommended for destroying the 



Fig. 44. — The Wheat Midge or Ply {Cecidomyia tritici). 



A. LarvsB feeding on wheat. 

 B and 0. LarvsD (nat. size and enlarged) . 

 D and E. Tlie Uy (nat. size and enlarged). 



larvsB, etc., of this pest. (2) Applications of lime, or a 

 mixture of soot and lime, are also recommended for the 

 same purpose. 



The Wheat Midge (Cecidomyia tritici, Pig. 44) be- 

 longs to the same genus, and is therefore a near relative 

 of the Hessian fly. It is a small, pale, orange-coloured 

 fly, with clear, almost veinless wings. The female fly 

 visits the florets of the wheat just as they are opening, 

 and deposits its eggs amongst the reproductive organs of 

 the florets, by means of a long, extensible ovipositor. The 

 eggs (which are oblong and transparent) are hatched in 



