INSECTS 



205 



Several African and Eurasian species are migratory, and return 

 movements occur rather frequently. Schistocerca grcgaria Forsk. has 

 been studied; it exists in two phases, the so-called migratory form 

 and the solitary form. The coloration and the structure of the prono- 

 tum distinguish the two phases, while comparable features also cliar- 



FiG. 47. — Showing the breeding areas of the grasshopper, migrants of 1876 and 

 the 1877 return flight. (After Packard, 1880.) 



acterize the nymphs. The normal distribution of this species covers 

 the arid grassland and semidesert areas of Africa and southern and 

 western Asia. Uvarov (1928) states that Kunchel's list of food plants 

 contains more species avoided than eaten, but asserts that the caper 

 plant [Capparis aphylln), the ornamental casuarina tree, and all 

 standing crops suffer. Dr. Richard LePelly writes in a personal com- 

 munication that the insects when swarming in Africa alight and feed 



