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EVOLUTION OF ANIMALS 



Part V 



Fig. 30.6. Monarch butterflies (Donaus menippe) resting while on an autumn 

 migration. They rest at night and whenever the wind is strong. (Photograph by 

 Hugh Halliday. Courtesy, National Audubon Society.) 



(Thysanura) and the springtails (Collembola). (2) With gradual or incomplete 

 change of form or metamorphosis — the wings developing as external pads; 

 in the immature stages the young are called nymphs. Grasshoppers, crickets, 

 cockroaches, cicadas, squashbugs, dragonflies, mayflies and others develop in 

 this way. Nymphs usually feed in the same manner and on the same food as 

 the adults. (3) With complete change of form or metamorphosis, the wings 



