DRAGON-FLIES AND THEIR LARVAE. 



These are popularly known by the names of horse- stingers 

 and dragon-flies. The former name is founded on a vulgar 

 error, since the animal has no sting. The illusion implied by the 

 latter is, however, more correct, since the insects, both in their 

 appearance and voracious habits, are certainly more entitled to the 

 name of dragons than that of demoiselles, or lady-flies, by which 

 they are commonly known in France. 



Fig. 1. 



The beautiful appearance of these insects on the wing, their 

 varied colours, the gauze-like structure of their wings, and the 

 rapidity of their flight, must have attracted general attention. 

 In hot summer days, they may be seen darting backwards and 

 forwards in the air over standing pools, which supply them 

 abundantly with the insects on which they feed. Their colours 

 are subject to much diversity, the males having an abdomen of 

 leadish blue, while that of the females is a yellowish brown. In 

 some species, the males have a rich bright blue colour, with black 

 wings, while the females are distinguished by a fine green, with 

 colourless wings. 



After impregnation, the female hovers over the surface of the 

 water until she selects a place for the deposition of her eggs, 

 which she deposits one by one in the water, beating the surface 

 with her tail while she lays them, until at length they are col- 

 lected into a mass resembling a bunch of grapes. 



The larvae on issuing from the egg are so minute as to be 

 scarcely perceptible to the naked eye. In some days, however, 

 they attain the length of the tenth of an inch, and cast their skin 

 for the first time. To the naked eye they appear in this state 

 like black spots, to which a tail is attached. When well fed they 

 grow rapidly ; and when they have attained the length of about 

 a quarter of an inch, they begin to display their characteristic 

 courage and ferocity, attacking, with open mouth, creatures ten 

 times their own bulk ; and, when pressed by hunger, devouring 

 each other. 



