INSECTS AFFECTING GRAINS, GRASSES, ETC. 107 



where they are caught in post-holes sunk every few feet in the 

 bottom of the ditch. This method may be used to advantage 

 in plots of corn, cotton, or garden truck which has already 

 become infested, by running furrows around the field and occa- 

 sionally through it, and then driving the young hoppers toward 

 them, which may be readily done by a number of children armed 

 with branches. Where ditches containing water are available 

 the young hoppers may be very effectively destroyed by oiling 

 the surface of the water with kerosene emulsion and then driving 



\ 



FIG. 89. Hopperdozer with cloth back, showing construction. (After W. R. 

 Walton, Farmers' Bulletin 747, U. S. Dept. of Agriculture.) 



them into the ditches, for even if they succeed in crawling out 

 they will succumb to the oil. 



In pastures, small grains or any crops permitting their use, 

 immense numbers of the nymphs may be caught by the use 

 of hopperdozers, which may be utilized where the use of poisoned 

 bran would not be possible. The hopperdozer consists of a 

 shallow pan containing water with a surface of kerosene, crude 

 petroleum, or coal tar, which is sometimes used without water. 

 The pan is mounted on runners or wheels and if larger than about 

 3 feet square is usually provided with partitions to prevent 

 slopping. The back and sides are high and sometimes are made 

 of canvas. "A good cheap pan is made of ordinary sheet iron, 

 8 feet long, 11 inches wide at the bottom, and turned up a foot 



