CH. IV] DEAGONFLIES 111 



Emergence very often takes place in the early morning or 

 may even begin before sunrise. It is clearly advantageous 

 that the helplessness of the soft-bodied imago should be 

 shrouded by the morning twilight from the eyes of in- 

 sectivorous birds and other animals. Even when the 

 wings are strong enough for flight, and the Dragonfly sails 

 off through the air, the final appearance has not been 

 reached, for there is a glossy sheen upon the surface of 

 the wings themselves and the body lacks the full splendour 

 of its colouring. This " immature " condition lasts one or 

 two or several days, during which the insect often seems 

 to avoid the ponds and streams. It is not known by what 

 process or cause the "mature" appearance is assumed. 

 There is evidence to show that, so far as the wings are 

 concerned, it in some way depends upon the chief nervures 

 being intact, for there is a record of a Dragonfly three of 

 whose wings were " mature " while the fourth, which had 

 suffered an injury to one of the principal nervures, and was 

 therefore incapable of being used, remained " immature." 



The life of the imago seldom lasts more than about 

 three months. In England all die before the winter. 



Enemies. As larvae, especially when small and after 

 each moult, Dragonflies probably fall frequent victims to 

 fish ; in aquaria they certainly devour one another and 

 are attacked by predaceous aquatic insects, e.g. the larvae 

 of the large Water Beetle, Dyticus marginalis. The 

 imagines are likewise at times guilty of cannibalism, the 

 larger species catching their weaker brethren. A few 

 birds have been observed to prey upon them, notably 

 kestrels, hobbies and swallows, while Gilbert White and 



