Practical Considerations. 



157 



I kerosene, and then ignited and carried over a field, near 

 I the ground, will slaughter large numbers. 



2. Crushing. — This can be resorted to with advantage 

 only in exceptional cases, where the ground is smooth and 

 hard. Heavy rolling, where the surface of the soil is 

 sufficiently firm and even, destroys a large number of 

 the newly-hatched young, but is most advantageously 

 employed when they are most sluggish and inclined to 

 huddle together, as during the first eight or ten days after 

 hatching, and in the mornings and evenings subsequently. 

 In many parts of Europe and Asia, flat, wooden, spade- 

 like implements are extensively used for this purpose. 



3. Trapping. — This is very effectual, especially when 

 the insects are making their way into a field from roads 

 and hedge-sides. The use of nets or seines, or converging 

 strips of calico or any other material, made after the plan 

 of a quail-net, has proved most satisfactory. By digging 

 a pit, or boring a post-auger hole three or four feet deep, 

 and then staking the two wings so that they converge to- 

 ward it, large numbers of the locusts may be driven into 

 the pit after the dew is off the ground, or may be headed 

 off when marching in a given direction. By changing the 

 position of this trap, much good can be done when the 

 insects are yet small and concentrated in particular spots. 



Ditching or trenching will come under this head ; and 

 after the insects have commenced to travel in schools, 

 proper ditching is the most effectual protection to crops. 

 This is especially true where, as was the case in much of 

 the ravaged country in 1875, there is little or no hay or 

 straw to burn ; or when the crops have grown to such a size 

 as prevents the use of some of the destructive agents men- 

 tioned further on. A ditch two feet wide and two feet 

 deep, with perpendicular sides, offers an effectual barrier 

 to the young insects. It must, however, be kept in proper 



