22 ON THE ORIGIN AND [CHAP. 



witnessing this marvellous change, and it is really won- 

 derful how rapidly it takes place : from the moment 

 when the skin first cracks, not ten seconds are over 

 before the insect has flow r n away. 



Another family of Neuroptera, the Dragon-flies, 

 or Horse-stingers, as they are sometimes called, from 

 a mistaken idea that they sting severely enough to 

 hurt a horse, though in fact they are quite harmless, 

 also spend their early days in the water. The larvae 

 are brown, sluggish, ugly creatures, with six legs. 

 They feed on small water-animals, for which they 

 wait very patiently, either at the bottom of the 

 water, or on some aquatic plant. The lower jaws 

 are attached to a long folding rod ; and when any 

 unwary little creature approaches too near the larva, 

 this apparatus is shot out with such velocity that the 

 prey which comes within its reach seldom escapes. 

 In their perfect condition, also, Dragon-flies feed on 

 other insects, and may often be seen hawking round 

 ponds. The so-called Ant-lions in many respects 

 resemble the Dragon-flies, but the habits of the 

 larvae are very dissimilar. They do not live in the 

 water, but prefer dry places, where they bury them- 

 selves in the loose sand, and seize with their long 

 jaws any small insect which may pass. The true Ant- 

 lion makes itself a round, shallow pit in loose ground 

 or sand, and buries itself at the bottom. Any inatten- 

 tive little insect which steps over the edge of this pit 

 immediately falls to the bottom, and is instantaneously 

 seized by the Ant-lion. Should the insect escape, and 

 attempt to climb up the side of the pit, the Ant-lion 

 is said to throw sand at it, knocking it down again. 



One other family of Neuroptera which I must 



