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MISSOURI AGRICULTURAL REPORT. 



After feeding and growing for a time this young chinch bug again sheds 

 its skin. This is the third molt ; and this stage of the young bug, which 

 is its fourth stage since leaving the egg, is sometimes spoken of as the 

 pupa stage, since it is next to the adult stage. But in reality there is 

 no true pupa in this case, because these insects develop by means of an 

 incomplete metamorphosis, and, therefore, these younger stages should 

 all be known as nymphs. See figure 51, ^, and figure 52, e. This so- 

 called pupa has a brownish-black head and thorax, and the little wing 

 pads that made their appearance in the previous stage are now larger. 

 The abdomen is dingy gray in color, with a dark horny spot at the tip. 

 When this insect has reached its proper size, the skin again splits open 

 along its back, and the adult insect comes forth. See figure 51, cut at 

 left, and figure 52, /. 



This adult insect has, as a rule, well developed wings extending 

 practically the length of the body, but in some instances the wings seem 

 to be aborted, so that they are not fit for use as organs of flight. By 

 observing a great number of adult chinch bugs, one can find various 

 stages, from the adults with very short and useless wings, to the adults 

 ■with long, normal wings, that are of service as organs of flight. The 

 adults are about three-twentieths of an inch in length, and the body is 

 of a black color, with a very fine grayish down. This down can be readily 

 seen under a magnifying glass, but is not visible to the ordinary naked 



Fig. 53. — Chinch Bug, Blissus leucopterus. Adults of short-winged form — much 

 enlarged. (From Webster, U. S. Dept. Agric.) 



eye. The wings and the wing covers are white, and the wing covers 

 have two irregular black lines and a black spot near the margin. By 

 referring to figures 51 and 52, one can obtain a fairly good idea of the 

 general shape and comparative size of the diflferent stages of chinch 

 bug, from the time they hatch, up through the various stages that I have 

 just described to the adult bug. While the figures show simply the com- 

 parative or relative size and the general markings, they do not show the 



