478 THE SMALL GRAINS 



piercing the epidermis, sucking the sap, and killing the 

 tissue around the wound. 



524. Description and life history. There are two 

 broods of the chinch bug. During winter the mature 

 winged insects of the last preceding brood hibernate in 

 dead grass and under various kinds of rubbish. In the 

 spring they leave winter quarters and locate in wheat and 



FIG. 150. Several stages or instars in the life history of the chinch 



bug. 



other small cereals. There the young are produced in 

 May and June, and mature just after harvest. With the 

 disappearance of their small-grain food supply, they mi- 

 grate into the nearest corn or sorghum fields. There a 

 new brood is produced that matures in the autumn. 



There are 6 stages in the life history of the chinch bug. The 

 egg is less than T V inch long, cylindrical, blunt at one end, pale or 

 whitish at first, later showing color through the shell. The newly 

 hatched larva is little larger than the egg, of a pale reddish color, 

 and resembles the adult, except in having no wings. On molting 

 there is a second larval stage or instar resembling the first, but 

 larger and having the head and thoracic segments darkened and 

 hardened. The third instar is still larger and the head and thorax 

 still darker and more coriaceous. After a third molt, the fourth 

 instar or the pupal stage is reached, resembling the adult almost 

 entirely, but there are still mere pads instead of wings. Next there 

 is the perfect insect which is black with white spots on the wings. 

 The life cycle requires nearly two months (Fig. 150). 



