GENERAL ZOOLOGY 



Fig. 15.14. The Eastern lub- 

 ber locust, Rhomalea microplera. 

 (Photoe;raph courtesy New 

 York Zoological Society) 



sounds of the day, just as the stridulations of their near relatives, the katydids 

 and crickets, are among the most familiar nocturnal sounds. Some locusts are 

 non-migratory, spending their entire lives in a single field. Other species, or 

 other races of the same species, may be migratory, breeding in one locality and 

 moving to another. In the migratory forms the young hatch in May or June, 

 depending on climatic factors, and migration begins within a few hours. The 

 animals move in great swarms; since the wings have not yet developed at this 

 stage, the animals progress by hopping and by crawling rapidly over the 

 ground. Crossing a cultivated field, the swarm consumes all the plants, even 

 to the roots; yet it may pass on to barren land beyond, without destroying 

 the growth of plants on either side of its line of travel. As the individuals in 

 the swarm reach maturity and their wings become fully developed, the swarm 

 can take to the air and move for miles in such numbers that they obscure 

 the sun. 



General Structure. The body is conspicuously divided into the three 

 regions typical of insects: the head, the thorax, and the abdomen (Fig. 15.15). 

 The abdomen shows eight well-defined segments, with portions of at least 

 three additional posterior somites. There are, as in other insects, three 

 thoracic segments, the prothorax, mesothorax, and metathorax, each bearing 

 a pair of legs. The number of segments in the head is problematical, but 

 there is clear evidence of at least four somites. The body is completely en- 



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