THE HESSIAN FLY. 



49 



and sometimes exceed thirty in number. They are generally 

 arranged in the longitudinal depressions between the minute 

 ridges of the blade. Their appearance is that of very small 

 reddish coloured points or spots. Their length is consid- 

 erably greater than their diameter, and appears to bear the ratio 

 to the latter dimension of five to one, the length being about 

 one fiftieth of an inch, the breadth or diameter about one-two- 

 hundred-and-fiftieth. The form is cylindrical. 



78. The eggs of the autumn brood are hatched within a week 

 of the time they are laid, if the weather be warm ; during the 

 prevalence of cold and unfavorable Aveather they may remain 

 unhatched for a period of three weeks. The white colored mag- 

 got as soon as it is liberated from the egg, passes down the leaf, 

 between the sheath and stem, until it reaches the first joint, (the 



crown) ; here it becomes stationary 

 and apparently fixed upon the 

 stem (Fig. m and Fig. a §Jpar. 80), 

 nor does it change its position un- 

 til it assumes the form of the 

 inert worm or its pupa.'(n) It re- 

 poses with its head towards the 

 root of the plant. 



79. "When young autumnal wheat is attacked by one or more 

 of the maggots, the infested shoots will be seen in the following 

 spring to be withered and changed to a straw colour. If two or 

 more shoots proceed from the crown of the root, those only to 

 which the maggot is attached will wither and die. In young 

 plants, death of the part affected is produced by the abstraction 

 of the nutritious juices which would otherwise be appropriated 

 to the nourishment of the shoot. The increased power of ab- 

 sorption and assimilation of food possessed by the plant when 

 the spring brood of the fly appears, (in May,) enables it to re- 



(FIG. m.) 



(FIG. ».) 



