INSECTS INJCUIOLS TO THE GRAINS AND GRASSES. To 



Duelling. — Of the various means devised for trapping 

 the nymphs "ditching" is one of the best, and is of 

 especial advantage when the crops become too large for the 

 effective use of other methods. Simple ditches two feet 

 wide and tw^o feet deep, with nearly perpendicular sides, 

 form effectual barriers to young grasshoppers. The sides 

 next to the field to be protected must be kept finely pul- 

 verized and not allow^ed to become washed out or hardened. 

 This may be done by a brush composed of dead branches 



Fig. 47. — Simple Coal-oil Pan or Hopperdozer. (After Riley.) 



being hauled through the ditch, which has been dug in a 

 strip of finely pulverized soil. The young locusts tumble 

 into the ditch, and, failing to climb the steep and slippery 

 sides, die there, from their exertions and the heat, in large 

 numbers. To avoid too great an accumulation, pits should 

 be sunk in the ditch at short intervals, in which most of 

 them will accumulate, and wdiere they may be easily 

 buried. It would seem that grasshoppers w^ould be able 

 to leap across such a small obstacle, but as a matter of 

 fact, like the Chinch-bugs, which might fly across^ they 

 very seldom do so. 



