74 LOWER PTERYGOTA 



Order ODONATA. 



This group includes the dragon flies and (himsel flies, 

 insects with incomplete metamorphosis, biting mouth parts, 

 and large, net-veined wings without folds. 



The larv{3e of these dragon flies and damsel flies are aquatic 

 and distinctly predaceous, feeding on aquatic animals. 

 The adults are also predaceous and catch insects in flight 

 very readily. The former, particularly, have very swift, 

 rapid flight, and may be seen darting here and there, espe- 

 cially in the vicinity of water, while the latter fly somewhat 

 more slowly. Both groups catch insects and feed upon 

 them, and so they are thought of as being beneficial, since 

 many of the insects that they feed upon are destructive. 



The eggs in all cases are laid close to the water's edge, 

 either at or jusc above the surface, or in some cases attached 

 to stems of water plants beneath the surface. When the 

 larvae hatch they are already under water and can begin 

 their active life, preying upon the aquatic animals. In 

 both adult and larval stages the mouth parts are provided 

 with strong mandibles fitted especially for biting. In the 

 larval or nymphal stage there is a very peculiar enlargement 

 and elongation of the labium, so that it becomes a large 

 mask for the front part of the head, covering the outer 

 mouth parts and lower part of the face. These are provided 

 with a pair of very strong, clasping, or pincer-like organs, 

 which are used in capturing the aquatic animals on which 

 they prey. The elongated and jointed structure of the 

 labium permits the insects to thrust this forward a distance 

 of about half an inch from the head, so that they can reach 

 out and capture animals that seem to be out of their reach. 

 These are snatched up very quickly and ground up with 

 their mandibles. 



After passing the larval stage they crawl out of the water 

 on the bank of the stream or pond or sometimes on the stem 

 of a plant, then the nymphal case splits along the centre 

 line of the back, the adults draw themselves out of this 



