THE HESSIAN FLY. 125 



17. (a) The Hessian Fly, (b) the Thrips, (c) Wheat 

 Stem Fly, (d) Wheat or Corn Saw Fly, (e) Wheat Para- 

 sites. (a) The Hessian Fly. Fortunately the farmers of 

 this country have not had as yet the same experience of 

 this terrible scourge of the wheat crop as the farmers of 

 North America, where at one time, in some of the States 

 of the Union bordering the Atlantic, its ravages were such 

 that the cultivation of wheat was likely to be altogether 

 arrested. Although not unknown in Europe, having been 

 under the cognizance of naturalists as existing in France, 

 Germany, Switzerland, and some of the larger islands of 

 the Mediterranean \ still its ravages have been confined so 

 much to America, that some naturalists have asserted that 

 it is strictly an American insect. The Hessian fly is so 

 called from the opinion at one time held in America that 

 it was introduced into that country in 1776 by German 

 troops taken over from Hesse, in Germany, to reinforce the 

 British army then in possession of Staten Island, near New 

 York. The insect is dipterous, not unlike the wheat midge 

 (see Fig. 14), but the antennae are shorter, the wings more 

 elongated, and the hind part of the body pointed. The 

 scientific designation of the insect is cecidomyia distinctor. 

 The fly lays her eggs on the leaves of the young wheat in 

 November and May. When this is done with autumn 

 sown wheat, the plants in spring assume a straw colour 

 and appear to be withered ; the shoots only to which the 

 maggot is attached wither thus. The maggots appear to 

 live by suction merely, as they do not incise the stem or 

 otherwise injure it. When the autumn maggot has arrived 

 at its full growth the outer skin becomes detached, and 

 serves as a case first for a larva, and secondly, for a pupa 

 or chrysalis case. The outer skin becomes hardened, and 

 within the protecting case the maggot remains throughout 

 the winter months. As spring approaches, the larva changes 

 into the pupa condition still within the same case and, 

 after remaining in this condition for eight or ten days, the 

 pupa works its way up through the soil to light and air, 

 where it emerges through the case, which now cracks, arid 



