158 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



Order Odonata. -The Odonata are the familar dragon-flies, 

 devil's darning-needles, and damsel-flies, that swoop about over 

 ponds and quiet streams, capturing small flying insects. The 

 body is long and slender, and the four wings are membranous, 

 many-veined, and all about equal in size. They live largely 

 on the wing and are among the most rapid and powerful insect 

 fliers. The legs are slender and weak, and chiefly used to hold 

 captured prey up to the mouth and for perching. Like the 

 May-flies and stone-flies, their young stages are spent in water 

 as wingless, crawling nymphs. Here also they capture smaller 



FIG. 71. Adult and last exuvia of the white-tail dragon-fly, Plathemis 



trimaculata. (Natural size.) 



living insects, not however by speedy pursuit but by lying in 

 wait and seizing any unwary prey that may come within reach 

 of the curious extensile under lip which is provided with sharply 

 toothed, jaw-like pincers. 



About 300 species of Odonata are known in North America, 

 and 2000 in all the world. All of them have beautifully 

 colored bodies, and many have the wings strongly patterned 

 by conspicuous brown blotches and bands. None of them is 

 injurious to man, but almost all may be considered as beneficial, 

 because they are all destroyers of noxious insects. It is 



