NEUROPTERA 



285 



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 Sialidas of the world have been monographed by H. W. 

 Van der Weele ('lo). 



The family Sialidas is divided into two subfamilies; these can be 

 separated as follows : 



A. Ocelli wanting; fourth tarsal segment prominently bilobed; radial sector 

 not pectinately branched. Insects rather small, having an expanse of 

 wings of about 25 mm. p. 285 Sialin^ 



AA. With three ocelli; fourth tarsal segment simple, not bilobed; radial sector 



pectinately branched. Insects large or moderately large, p. 286 



corydalin.*; 



Subfamily SIALIN^ 



The Alder-Flies 



The alder-flies are so-called because the adults are commonly 

 found on alders on the banks of streams; this name was given to 

 them by English anglers. 



The subfamily Sialinae includes only two genera, both of which 

 are represented in this country, each by a single species. These 

 genera are distinguished as follows : 



A. Costal area of the fore wings greatly expanded before the middle (Fig.318). 



SlALIS 



AA. Costal area of the fore wings slightly expanded before the middle 



Protosialis 



2d A 

 Fig. 318.- 



ist A <~«i 

 -Wings of Sialis injumata. 



