48 



insect enemies, which kill them off in ordinary, seasons. With 

 changes of atmospheric conditions, however, the insect and fungous 

 enemies are frequently destroyed, and then the grasshoppers increase 

 in abundance. In such cases they can be destro3"ed b}^ several artifi- 

 cial methods. The remedies that have proved most efficient are: 

 (1) plowing under the eggs before these have had time to hatch, and 



Fig. -18. — A simple coal-tar pan to be drawn by hand (after Riley). 



(2) capturing the unfledged locusts, as well as man}' of those which 

 have become winged, by means of hopperdozers or kerosene pans. 



Ilopj)erdozers are necessary implements of warfare against most 

 grasshoppers. They are shallow sheet- iron pans, made of any size 

 most convenient, or canvas frames, mounted on runners to be drawn 

 over the ground either by a horse or by hand, preferably against the 



wind, in such a man- 

 ner that the grass- 

 hoppers will leap into 

 them and be killed by 

 coming into contact 

 with the tar or oil 

 which is poured into 

 them for the purpose. 

 Two forms of hop- 

 perdozers are shown 

 in figures 48 and 49. 

 Bran-arsenic nnix- 

 ture is another rem- 

 edy of great value in 

 the prevention of injury to our cultivated crops. The directions for 

 preparing this mash have been given under remedies for cutworms 

 (page 185). 



Fungous diseases as a remedy. — During the years 1901-2 the subject 

 of the possible control of grasshoppers by means of contagious diseases 

 was taken up by the Division of Entomology, and a report by Dr. 



Flu. rj.— A canvas hopperdozer to be drawn by horse (after Riley 



