224 Nerve-winged Insects; Scorpion-flies; Caddis-flies 



and in most cases given specific ordinal rank. Thus we now consider the 

 May-flies to from an order, the stone-flies another, the dragon-flies still 

 another, and so on. There are left, grouped together as the order Neu- 

 roptera, seven families which possess the common characteristics of netted- 

 veined wings (numerous longitudinal and cross veins), mouths with well- 

 developed biting or piercing jaws (mandibles), and a development with com- 

 plete metamorphosis. Further than this little can be said to characterize 

 the order as a whole, and we may proceed at once to a consideration of the 

 various distinct families. 



KEY TO THE FAMILIES OF NEUROPTERA. 



A. Prothorax as long as or longer than the mesothorax and the metathorax combined. 



B. Fore legs greatly enlarged and fitted for grasping MANTISPID.E. 



BB. Fore legs not enlarged and not fitted for grasping RAPHIDIID^E. 



AA. Prothorax not as long as the mesothorax and the metathorax combined. 



B. Hind wings broad at the base, and with that part nearest the abdomen (the 



anal area) folded like a fan when not in use SIALID^E. 



BB. Hind wings narrow at base, and not folded like a fan when closed. 

 C. Wings with very few veins, and covered with whitish powder. 



CON I OPT E RYGID^E. 



CC. Wings with numerous veins, and not covered with' powder. 



D. Antennae gradually enlarged towards the end, or filiform with a 



terminal knob MYRMELEONID.E. 



DD. Antennas without terminal enlargement. 



E. Some of the transverse veins between the costa and subcosta 

 forked (in all common forms), wings brownish or smoky. 



HEMEROBIIDvE. 



EE. Transverse veins between the costa and subcosta simple, 

 wings greenish CHRYSOPID.E. 



While most of the Neuroptera are terrestrial in both immature and adult 

 life, one family, the Sialidae, includes forms whose larvae are aquatic. There 

 are only three genera in the family, but all are fairly familiar insects to col- 

 lectors and field students. The adults of these genera can be distinguished 

 by the following key: 



Fourth segment of the tarsus bilobed; no simple eyes (ocelli) SIALIS. 



Fourth segment of the tarsus simple, cylindrical; three simple eyes (ocelli). 



Antennas with segments enlarged at the outer ends; hind corners of the head rounded. 



CHAULIODES. 



Antenna; with segments cylindrical; hind corners of the head with a sharp angulation 

 or tooth CORYDALIS. 



The larvae can be distinguished by the following key: 



Tip of abdomen bearing a single long, median, laterally fringed tail-like process. . SIALIS. 

 Tip of abdomen forked, the two fleshy projections each bearing a pair of hooks. 



Lateral filaments (soft, slender, tapering processes projecting from the sides of the abdom- 

 inal segments) with no tuft of short hair-like tracheal gills at base. ..CHAULIODES. 

 Lateral filaments each with a tuft of short, hair-like, tracheal gills at base . . CORYDALIS. 



