ARTHROPODA. 



301 



paired appendages. They carry pollen from flower to flower, effecting 

 cross-fertilization, in some instances. The color of the larvae and the 

 adults is very varied and has close relation to the environment and habits 

 of the animals. We have already noticed in the chapter on adaptations 

 (Chap. VIII) how the coloration may be protective. This is the more 

 needed since the group has many enemies, especially in the larval stage. 

 The power of reproduction is great. Several broods per year may be 

 produced. There are 25,000 known species of Lepidoptera, 6,000 of which 

 occur in North America, north of Mexico. The species are more numerous 

 and striking in the tropical regions of South America. 



Order Coleoptera (shield-wings}. In this group there is a complete 

 metamorphosis. The mouth parts are suited to biting and chewing. The 

 front wings (elytra} are hardened and serve as covers for the true mem- 



FIG. 146. 



FIG. 146. Swallow-tail Butterfly (Papilio machaon), larva, pupa, and adult. 

 From Nicholson. 



Questions on the figure. Which is the larva and which the pupa? 

 Which of these is the earlier stage? What are the chief characteristics of 

 the three stages in the metamorphosis of butterflies, the larva, the 

 pupa and the imago? 



