

CHAPTER XX 



NEUROPTERA PLANIPENNIA SIALIDAE, ALDER-FLIES, SNAKE-FLIES 



PANORPIDAE, SCORPION -FLIES HEMEROBIIDAE, ANT-LIONS, 



LACEWINGS, ETC. 



Fam. VIII. Sialidae Alder-flies and Snake-flies. 



Four ivings of moderate size, meeting in repose over the back at 

 an angle ; the hinder of the two pairs slightly the smaller ; 

 the anal area small or nearly absent, not plicate. Nervures 

 moderately numerous, transverse veinlets moderately numerous, 



forming irregularly disposed cells. The metamorphosis is 

 great; there is a quiescent pupa. The larva has the mandibles 



formed for biting, armed with strong teeth. 



THE Sialidae, though but a small family of only some six or 



eight genera, comprise 

 a considerable variety of 

 forms and two sub- 

 families Sialides and 

 Raphidiides. The former 

 group has larvae with 

 aquatic habits possessed 

 of branchiae but no 

 spiracles. 



Sialis lutaria is one 

 of the commoner British 

 Insects frequenting the 

 vegetation about the 

 banks of tranquil streams; 

 FIG. 286. The alder-fly, Sialis lutaria. Britain. j^ j g \yell kllOWll to 

 A, With wings expanded ; B, in profile. 



anglers, being used by 

 them for a bait. According to Ronalds it is called the alder or 



