68 



THE STUDY OF INSECTS 



Family Sialid.-e 

 The Sialids 



The members of the Sialidrc differ greatly in size and appearance; 

 but they agree in having the hind wings broad at the base with the anal 

 area folded like a fan when not in use. In this respect they differ from 

 all other Neuroptcra. 



The larva? are aquatic, predatory, and possess paired, lateral fi la- 

 ments on most or on all of the abdominal segments. They leave the 

 water when full-grown and transform in earthen cells on the banks of 

 the streams or lakes in which they lived as larvae. The eggs are deposited 

 in clusters on any convenient support near the water, in such situations 

 that the young larvae can easily find access to the water. The adults 

 fly but little; they are most often found resting on some support near 

 the water, with the wings folded over the abdomen. 



The smoky alder-fly, Sialis infumdta, is a dusky-brownish small 

 insect with a wing-expanse of about one inch. Its eggs are laid in 

 patches on objects near or over the water. The larva lives beneath 

 stones in swiftly flowing streams. It has paired lateral filaments on the 



Fig. no. — Larva of 

 the smoky alder-fly. 



Fig. in. — Corydalus cornulus. 



Fig. ii2. — Corydalus cor- 

 nuius, larva. 



first seven abdominal segments and the last abdominal segment is pro- 

 longed into a tapering lash-like filament (Fig. no). 



The species that is most likely to attract attention is the horned 

 corydalus, Corydalus cornutus. This is a magnificent insect, which has a 

 wing-expanse of from four to nearly five and a half inches. Figure in 

 represents the male, which has remarkably long mandibles. The female 



