120 ZOOLOGY. 



diers, the latter with large heads and long Jaws. The white 

 ants in Africa bi^ild conical hills six feet or more in height. 

 Order 5. Odouata. — Dragon-flies (Pigs. 146, 147) rep- 

 resent this order. They have broad, net-veined wings and 

 free biting mouth-parts. The metamorphosis is incomplete, 

 the pupfe (Fig. 148) being active and feeding on smaller 

 insects, only differing from the larvas in having rudiments 



Fia. 148.— Pupa of a Dragon-fly Fig. 149.— May-fly and larva, the latter 



(jEschna). enlarged. 



of wings. Dragon-flies are constantly on the wing in 

 pursuit of insects; they are sometimes called "mosquito 

 hawks." 



Order 6. Pledoi^era. — May-flies (Fig. 149) are so called 

 from their shortness of life, as they live but a day or two. 

 The young live in the water, and breathe by feathery gills 

 on the side of the body. 



