31G 



AN INTRODUCTION TO ENTOMOLOGY 



eggs in long gelatinous strings, on some plant stem at the surface of 



the water. 



The metamorphosis is incomplete. The naiads are all aquatic 



except those of a few Hawaiian damsel-flics, which live on moist soil 

 under the leaves of liliaceous plants. The wings 

 are developed externally, and the development of 

 the compound eyes is not retarded, as it is with 

 larvae. The adaptations for aquatic life differ in 

 the two suborders and are described later. 



All naiads of the Odonata are predacious. 

 The mouth is furnished with well-developed 

 mandibles and maxilke, all of which are armed 

 with strong teeth. But none of these is visible 

 when the insect is at rest. The lower lip is greatly 

 enlarged, and so formed that it closes over the 

 jaws, concealing them. For this reason it has been 

 termed the mask. But it is much more than a 

 mask; it is a powerful weapon of offence. It is 

 greatly elongated and is jointed in such a way that 

 it can be thrust out forward in front of the head. 

 It is armed at its extremity with sharp hooks, 

 for seizing and retaining its prey (Fig. 360). 



The order Odonata is divided into three sub- 

 orders. One of these suborders, the Anisozygop- 



Fig. 360. — Underside tera, is composed almost entirely of fossil forms, 



of head of a naiad being represented among living insects by a single 



of a damsel-fly with genus, Epiophlehia, which is found in Japan. The 



(After Sharp.) other two suborders are well represented m this 



country; one of them consists of the dragon-flies, 



the other of the damsel-flies. 



Suborder ANISOPTERA* 



The Dragon-Flies 



The dragon-flies 

 are easily recognized 

 by the relative size of 

 the two pairs of wings, 

 and by the attitude of 

 the wings when at 

 rest (Fig. 361). The 

 hind wings are larger 

 than the fore wings 

 and are of a somewhat 

 different shape; but 

 the most striking 

 characteristic is the 

 fact that the wings 

 are extended horizontally when at rest 



Fig. 361. — A dragon-fly, Libellula luctuosa. 



" Anisoptera : anisos {Uvuroi), unequal; pteron {irrephv), a wing. 



