U4 THE BOOK OF NATURE STUDY 



the pond in which the larval life was spent. All four wings are 

 covered with fine hairs, and the antennae are long. 



The chief object of the adult life is to provide for the pro- 

 pagation of the species. The female lays a mass of eggs contained 

 in a jelly in a pond or stream, and from these eggs the little larvae 

 emerge. They are at first very active, and begin at once to 

 construct a case. With the approach of winter they become 

 sluggish, and hide under stones, etc. In spring they again be- 

 come active, and pupate, as stated above, in early summer. 



As we have given the life-history of the caddis with some 



fulness, less detail is necessary in the case of gnats and dragon-flies. 



The dragon-fly is interesting because the metamorphosis 



is of the type called incomplete ; in other words, no quiescent 



pupa stage separates the larva from the winged imago. 



To obtain specimens of the larvae recourse should be had 

 to a pool over which the beautiful adults have been seen flitting. 

 From such ponds take with the net a good supply of mud and 

 water weeds, and some of the larvae will be probably found among 

 the contents of the net. Put the larvae in a shallow dish, with a 

 layer of mud at the bottom, and some weed, and supply them 

 with abundant animal food, such as aquatic worms, beetle larvae, 

 or almost any pond creature of suitable size, and there will be no 

 great difficulty in rearing them to the imago stage. They are, 

 however, dangerous inhabitants of the general aquarium, if this 

 contain delicate animals, as they are exceedingly voracious. 



Two types of dragon-fly larvae occur, the large dragon flies, 

 like Libellula, having larger and much more powerful larvae than 



the more delicate form belong- 

 ing to the Agrionidce. Taking 

 one of the former first, we 

 find that the body is broad, 

 especiallv in the abdominal 



FlG. 51. Libellula larva with extended mask. Jr . 



region. The large head has 



two distinct eyes and short antennae, and is also furnished with a 

 peculiar organ known as the mask. This is the means by which 

 the larvae obtains its food, and is a development of the lower lip 

 of other insects. In the resting position it is carried over the face, 

 being bent and doubled upon itself. If some small animal capable 



