ix DRAGON-FLIES 331 



The larva: inhabit water, for the most part standing 

 water, where they subsist by capturing living animals 

 of all kinds, Insects, Snails, Tadpoles, and even 

 Fishes. The skin is moulted several times during 

 this stage, which is believed to occupy as a rule a 

 year or more. For some time before the emergence 

 of the winged Insect, the rudiments of the wings 

 become externally visible, and in this state the Insect 

 is sometimes called a pupa. There is, however, no 

 stage corresponding to the resting-stage of the 

 Lepidoptera. 



The larvae of the numerous species of Dragon-fly 

 exhibit external features by which it is easy to 

 distinguish and group them. Some of the smaller 

 species have three pointed, semi-transparent plates 

 (tracheal gills) projecting from the end of the body. 

 These are recognised at a glance as Agrionidae. In 

 the remaining Dragon-fly larvae, the tracheal gills 

 are not conspicuous. If the abdomen is compara- 

 tively broad and flat, and shorter than the hind legs, 

 we know that the larva belongs to the Libellulidae. 

 In ^Eschnidae the abdomen is slender and longer 

 than the hind legs. 



The larva is not at all nimble. It often remains 

 for hours nearly motionless, clinging with its legs to 

 some water-weed. When it walks, the movement is 

 steady but not rapid. It has another mode of loco- 

 motion which may be called swimming. In larvae 

 of Agrionidae the abdomen is bent first to one side 

 and then to the other. This sculling movement 

 drives the body forwards with moderate speed. 

 Libellulid larvae can propel themselves more rapidly, 



