CEREAL PESTS INSECTS 479 



525. Control measures. The chinch bug is most 

 easily destroyed at two periods, (1) during hibernation in 

 winter, and (2) at the time of migration of the first brood 

 from small grain to corn or sorghum. All near-by grass 

 lands and waste places should be burned over early in 

 the winter, so that the bugs not killed by the fire may 

 be exposed as long as possible to winter freezes. All 

 rubbish in fence corners and in hedge-rows should be 

 raked out and burned. These operations will prevent 

 swarms of mature insects going into small grain in the 

 spring. 



In midsummer \vhen the mature bugs of the first brood 

 attempt to migrate from the small grain, dust barriers 

 formed around the infested fields are very effective. These 

 are strips of plowing 10 to 15 feet wide, which are thor- 

 oughly worked into a fine dust mulch. The heat destroys 

 many bugs that attempt to pass over the barrier, and the 

 hot, fine dust closes breathing pores and smothers those 

 not killed by the heat. The surface must be kept con- 

 stantly stirred into a fine condition. Also a ditch may be 

 plowed, throwing the dirt both ways, and a log dragged 

 through it back and forth, making a bed of fine dust in 

 the bottom. Few bugs will cross the ditch. 



In wet weather, when dust will not form, effective 

 barriers of oil or tar may be made. First, a well-packed 

 ridge should be made. Then, by using a sprinkling can 

 with the sprinkler removed, or by attaching a hose to a 

 barrel, a thin line of coal tar or thick road oil an inch or 

 less wide is run along the ridge. The bugs will not pass 

 over this line. It is kept fresh by adding more oil or tar 

 once or twice a day, later once in 2 or 3 days. If post 

 holes are made about every 20 feet on the side of the 

 line next to the infested field, the bugs, repelled by the 



