70 



GENERAL ZOOLOGY 



A nymph when mature crawls out of the water, splits up 

 the back, and an imago emerges from the old skin. The 

 adult may-fly lives only a day or two and keeps fluttering 

 along the shore, looking for a mate or laying eggs. Its 

 mouth parts are so rudimentary that it is wholly unable to 

 eat. 



Order 3. Odonata (Fig. 38). This order includes the 

 dragon-flies and damsel-flies. Both are largely aquatic, lay 



ODONATA CPHCMfLRIDA TRICHOPTEHA PLECOPTERA 



FIG. 38. Showing the immature and adult stages of the four chief orders of 



aquatic insects. 



their eggs in the water, and have a heterometabolous 

 metamorphosis. Damsel-fly larvse have three paddle-like 

 gills at the end of the abdomen. The adults are sly little 

 insects which fold their gauzy wings up over their backs 

 when at rest. Dragon-fly larvse have three short spines 

 at the end of the abdomen. They swim by drawing water 



