224 AN INTRODUCTION TO ENTOMOLOGY. 



The genus Sisyra is anomalous in that its larvae are aquatic. We 

 have a single species described from Georgia. This is a small insect, 

 having an alar expanse of only 9 mm. (0.35 inch). 



Polysicechotes is confined to this continent. These are larger 

 insects, having an alar expanse of from 50 to 75 mm. (2 to 3 inches). 

 They are nocturnal, and are attracted to lights. Two species have 

 been described. P. punctdtus is our most common one ; it is black- 

 ish, with three longitudinal lines on the disk of the prothorax, and 

 the lateral margins of this segment yellowish. P. vittdtus is pale 

 yellowish, with a black stripe on the sides of the thorax, and with 

 the abdomen dark brown. The larva of neither of these species is 

 known. They are probably aquatic. 



Micromus includes smallish species having an alar expanse of 

 from 10 to 20 mm. (0.4 to 0.8 inch). My personal experience leads 

 me to believe that they are rare ; and I find no published accounts 

 of the appearance and habits of the larvae. 



Hemerobius is much better known ; although the spec.ies of this 

 genus are not common. More than twenty North American species 

 have been described. These are also smallish insects ranging in 

 alar expanse from 8 to 20 mm. (0.3 to 0.8 inch). They occur in 

 forests, and especially on Coniferous trees. The larvae bear a strong 

 resemblance to the Aphis-lions ; and like them feed upon Aphids 

 and other small insects. After sucking the fluids from their victims, 

 they make a cloak for themselves of the empty skins. 



Sub-family III. CHRYSOPIN.E. 

 (Lace-winged Flies or Aphis-lions.} 



Nearly all of the species of this sub-family pertain to the genus 

 Chrysopa. These insects are known in the adult state as Lace-winged 



FJG. 192. Chrysopa, eggs on stalks, larva, and adult 



Flies, and in the larval form as Aphis-lions. The antennae of the 

 adult are long and setaceous ; the venation of the wings resembles 

 somewhat that of the preceding sub-family ; but the subcostal and 



