124 



INJURIOUS IKSECTS 



gots, about one-twelf til of an inch long, and of an orange 

 color, among the forming grain, which are popularly 

 known as midges, a portion of the larva3 or midges go 

 into the ground and pupate, while others are harvested 

 with the grain. Some parasitic insects help reduce the 

 numbers of the midge, and so far as is known, deep 

 plowing, to turn those which have entered the ground 

 so deep that they cannot make their way to the surface, 

 and the burning of the refuse in the cleaning of the grain, 

 are the only artificial helps suggested. 



THE JOINT-WORM. 



{Isosoma hordei, Harris.) 



In certain years and in particular States the crops of 

 wheat, of barley, or of rye are greatly injured by a minute 

 maggot, popularly known as the Joint- worm." This 

 maggot is but little more than one-eighth of an inch 

 long, and of a pale-yellow color with the exception of the 

 jaws, which are dark-brown. It inhabits a little cell, 

 which is situated in the internal substance of the stem of 

 the affected plant, usually a short distance aboye the first 

 or second knot from the root, the outer surface of the 

 stem being elevated in a corresponding elongate blister- 

 like swelling; and when, as is generally the case, from 

 three to ten of these cells lie close together in the same 

 spot, the whole forms a woody enlargement, honey-combed 

 by cells, and is in reality a many-celled gall. In figure 

 86, a, will be seen a sketch of one of these galls, the lit- 

 tle pin-holes being the orifices through which the flies 

 produced from the joint-worms have escaped. At first 

 sight, these knotty swellings of the stem are apt to elude 

 observation, because, being almost always situated just 

 above the joint or knot on that stem — whence comes the 

 popular name ' 'Joint-worms " — they are enwrapped and 

 hidden by the sheath of the blade; but on stripping off 



