300 



AN INTRODUCTION TO ENTOMOLOGY 



and well-known insects; they are found upon herbage and the foliage 



of shrubs and trees 

 throughout the summer 

 months (Fig. 339). 



The adults are easily 

 recognized by their deli- 

 cate lacelike wings and 

 their green or yellowish 

 green color. Members of 

 several of the preceding 

 families have delicate 

 lacelike wings; but with 

 those insects the wings 

 are more or less brown or 

 are hyaline. 



While these insects 

 are most commonly 

 known as the lacewing- 

 fiies, other popular names 

 have been applied to 

 them; they are some- 

 times called golden-eyed flies, on account of the peculiar metallic 

 color of their eyes while alive; and as some species, when handled, 

 emit a very disagreeable odor, they have been called stink-flies, an 

 undesirable name for such beautiful insects. 



The wings of the Chrysopidse are characterized by a very re- 

 markable and distinctive type of specialization, the details of which 



Fig. 339-— Eggs, 

 Chrysopa. 



larva, cocoon, and adult of 



Fig. 340. — Fore wing of Chrysopa nigricornis: ]M', pseudo-media; Cui', pseudo- 

 cubitus. 



can be understood only by a study of the tracheation of the wings 

 of the pupas. Such a study has been made by McClendon ('06), 

 Tillyard ('16), and R. C. Smith ('22). 



A superficial examination of a wing of Chrysopa (Fig. 340) reveals 

 the presence of two longitudinal veins between the radial sector and 

 the inner margin of the wing, one of which appears to be the media 

 and the other vein Cui; but each of these, as is shown later, is a 

 serial vein composed of sections of several veins. 



