DERMAPTERA 



461 



The compound eyes are rather large; but the ocelli are wanting. 

 The antennae are slender, and consist of from ten to thirty-five seg- 

 ments ; the second segment is always small. The fore wings are leath- 

 ery, very short, without veins, and when at rest meet in a straight line 

 on the back. This pair of wings is commonly termed the tegmina 

 or the elytra. The hind wings when at rest are folded both length- 

 wise and crosswise and project a short distance behind the fore wings 

 (Fig. 538). The radiating veins of the hind wings extend from a 

 point near the middle of the length of the wing (Fig. 539). When 

 the wing is not in use, that part over which the radiating veins ex- 

 tend is folded in plaits hke a fan. This part of the wing is the greatly 

 expanded anal area. The preanal area is much reduced with but 

 two longitudinal veins, and is quite densely chitinized. The trachea- 

 tion of the hind wings has been described and figured by the writer 



Fig. 539. — liind wing of an earwig: «/, nodal furrow. 



(Comstock '18). The wings vary much in size and development even 

 in the same species; and there are many species that are wingless. 

 The legs are similar in form, and the tarsi are three-jointed. 



The most distinctive feature of earwigs is the form of the cerci, 

 which are forceps-like, and usually very prominent. A similar form 

 of cerci is found, however, in the genus Japyx of the order Thysanura. 

 The size and shape of the forceps of earwigs differ in the different 

 species and in the two sexes of the same species; they are usually 

 more highly developed in the male than in the female ; they are used 

 as organs of defense and offense, in pairing, and are sometimes used 

 as an aid in folding the wings. 



