THE NEUROPTERA 197 



fisherman, have gained their scientific name of Ephemera from the 

 shortness of the life of the perfect insect, for the majority perish 

 within a few hours of attaining their full development. In the 

 perfect insect the mouth is quite rudimentary in structure, so that 

 the insect cannot take in any food, and the short hours of this 

 climax of its existence are devoted to sexual intercourse for the per- 

 petuation of its species. The larval and the active pupal or nymph 

 stage are passed entirely in the water, and appear to last for two or 

 three years, the skin during this period being cast several times. 



The life-history of the Dragon-fly, in which the early stages of 

 active larva and nymph are passed beneath the surface of the 

 pond, is too well known to need detailed description. Fiercely 

 carnivorous at every stage of their lives, the Dragon-flies help to 

 keep down many noxious insects, preying upon aquatic larvae, as 

 well as upon winged adult insects. In the larva and active pupa 

 or nymph stage, their movements are generally slow; but they 

 can also dart quickly by the sudden expulsion of water from the body. 



The Ant-lions (Myrmeleontida) are in the adult stage slender, 

 egant creatures, with large wings, not unlike a dragon-fly. The 



a, to which the name of "Ant-lion" properly belongs, is an 

 ly-looking insect, with a stout, short body, not in the least like 

 he graceful perfect insect. The larva can only walk backwards, 

 and in excavating the pit in which it lives it turns round 

 and round, throwing the sand grains out of its funnel-shaped 

 hole with the aid of its large, flat head. The sand, as it is 

 thrown over the sides of the pit, forms an unstable margin, so 

 that any wandering ant or other insect, stepping incautiously 

 upon it, starts some of the sand rolling, and itself struggles to 

 regain a firmer foothold. But the ant-lion at once begins to 

 throw up sand at its victim, which soon comes tumbling down and 

 is at once seized by the sharp mandibles of the ant-lion, which 

 are perforated by tubes, and allow the larva to suck the juices of 

 its prey. When the larva becomes fully grown it forms a silken 

 cocoon to the walls of which a quantity of sand-grains are glued, 

 and within this changes to a pupa, from which in due course the 

 perfect winged insect emerges. The larvae of Ascal aphides, al- 

 though closely resembling ant-lions in appearance, do not walk 

 backwards or form pitfalls for the capture of their prey, but hide 

 under fallen leaves and stones. 



