COMMUNITIES IN DRY, OPEN LANDS 459 



the steppe are burrowers. During the short moist period they must ac- 

 cumulate a food surplus (fat), and many Australian frogs (Cheiro- 

 leptes, Heleioporus) also store a water supply; they are distended like 

 a lemon, and investigation shows that their urinary bladder is filled 

 with clear water. 47 The natives know how to find these frogs in their 

 hiding places and use this water in time of need. 



Insects of the steppes. — Insects are found in enormous numbers. 

 Even during the dry season, they are not absent in grassland and 

 steppe, though their number is very much reduced. Three groups are 

 predominant, the grasshoppers, the ants, and, in the tropics and sub- 

 tropical areas, the termites. At times they have a major influence not 

 only on the organization of steppe life, since they afford a basic food 

 supply, but also on the landscape. 



No regions are richer in grasshoppers than grassland. Most of these 

 belong to the Acrididae; in Tripoli and Barka, 34 out of 72 species of 

 Orthoptera were acridids, 48 in the Transvaal, 42 out of 66. 49 Many 

 related groups rich in species and individuals are represented. Migra- 

 tory grasshoppers in myriads of individuals inhabit the steppe areas 

 of all continents (e.g., Stauronotus maroccanus in North Africa, Schis- 

 tocera peregrina in South Africa, S. paranensis in South America, 

 Melanopns spretus in North America, etc.). 50 They require a certain 

 alternation of dryness and moisture in order to thrive; their eggs be- 

 come moldy with too much moisture and dry up with too little, and 

 the newly hatched larvae with their thin exoskeleton likewise need 

 moist air and tender grass. Later on, moisture is their deadly enemy. 

 They are not able to exist for long in regions with long rainy seasons 

 (savannas, shrub areas of the tropics), and continually emigrate there 

 from arid regions, as adults, to last at most a few generations. They 

 avoid forest entirely. 51 The dry stretches of the subtropics and tem- 

 perate steppes are their natural habitat, and their maintenance in such 

 areas is due to the fact that the eggs may lie in the ground for several 

 years if there is too little moisture for hatching. Under favorable con- 

 ditions they appear in exceedingly large numbers and thereby become 

 a pest. They have been known to bring trains to a standstill in East 

 Africa and in western United States. The mature animals undertake 

 long flights in such large numbers that they rise into the air like dark 

 clouds. Where the females lay their eggs in the soil, the ground is so 

 full of burrows that it looks as though it had been recently worked by 

 man. 52 Their voracity laid waste the regions they entered in the Great 

 Plains of North America to such an extent that the bison were com- 

 pelled in earlier times to migrate. 53 Today in Russia, South Africa, 

 and elsewhere, they are kept in partial control by grasshopper patrols 



