(5o AN ECONOMIC ENTOMOLOGY. 



one to three years in this condition. Wing-pads gradually 

 appear, and eventually the adults emerge and fly away, only to 

 shed their skins once more in the very act of flight. I have seen 

 their delicate, pure- white exuviae float about over the Ohio River 

 in such numbers as to resemble a fall of snow. This moulting of 

 the adult is peculiar to the Ephemerids, who mate soon after it 

 occurs, deposit their eggs, and before morning perish, — their 

 life-work accomplished. 



Not all forms are so short-lived, however, some requiring sev- 

 eral days to complete oviposition ; but their inability to feed 

 indicates a brief existence at best. The number of species is large, 

 and the number of specimens immense, indicating an active, 

 aquatic insect life at least as great as that found in the air or on 

 the dry land. While the larvae feed on smaller creatures, they 

 are in turn devoured by fishes, who find in them an important 

 article of food, and in this view only are they of any economic 

 importance. 



Order ODONATA. 



Under this head come the dragon-flies, or, as they are often 

 termed, "devil's darning-needles," "spindles," or "snake- 

 doctors." Many superstitious beliefs are connected with these 

 insects, and there is a general indisposition to handle them, be- 

 cause of their supposed ability to sting. The insects are common 

 about ponds and streams, flying rapidly over the surface of the 

 water, occasionally darting down to touch its surface, and delight- 

 ing always in the bright sunshine. 



The body is long and slender, fitted with an enormous head 

 principally occupied by the eyes, and with two pairs of long nar- 

 row wings, which are similar in size and appearance. In some 

 species there are leaf-like appendages at the end of the abdomen, 

 and these are erroneously supposed to be weapons of oftence. 

 The legs are stout, clothed with spines and spurs, as well as with 

 long claws at the tip. The mouth is formed for biting, the man- 

 dibles and maxillae being greatly developed and sharp-toothed, 

 for tearing their prey. 



They are, as has been indicated, predaceous, and capture their 

 food during flight, their powerful wings and legs enabling them to 

 overtake and grasp any creature that comes within the range of 

 their huge eyes. Flies and mosquitoes are the usual victims, and 



