56 BRITISH INSECTS 



by a complex net veining, and in repose the wings 

 are held roof-wise over the insect's back. Metamor- 

 phosis is complete, a quiescent pupal stage always 

 preceding the final moult. Moreover, in this .order 

 we are introduced for the first time to insects whose 

 wings are developed inwardly (p. 12), the wing- 

 rudiments or " pads " not being visible until the pupal 

 stage is reached. The young are very different from 

 their parents, and may rightly be termed "larvae." 

 They are usually active, with well-developed thoracic 

 legs. Their mandibles are often grooved on the inner 

 edges, and through these grooves liquids can be drawn 

 into the mouth. Thus, while these larvae are typically 

 mandibulate insects, many of them really feed by 

 suction. So far as is known, all the species are 

 carnivorous, both in their larval and adult stages. 



British Neuroptera are divided into five families. 

 The alder-flies, 1 of which we have several species, are 

 dull-coloured insects. They may be represented by 

 the common alder-fly, 2 which figures in the angler's 

 list. The female lays her eggs in clusters on rushes 

 or grasses, usually near water. Immediately after 

 hatching, the larvae make their way to the nearest 

 pond or stream, and thereafter lead an aquatic life. 

 They have no spiracles, but are provided with pairs 

 of jointed gill-filaments on the first seven segments of 

 the abdomen, and a long unjointed gill-process at its 

 tip. By means of these appendages the larva breathes 

 the air which is dissolved in water ; and it is also able 

 to exist out of water, in a damp environment. It 

 feeds chiefly on small aquatic larvae, and when full 

 grown creeps out of the water. After burying itself 

 in the earth it changes to the pupa, from which the 



2 Sialis lutaria. 



