DERMAPTERA 



461 



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

 The antennas 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 fully developed, are large, with 

 radiating veins, and when at rest are folded both lengthwise and 

 crosswise. The folded hind wings 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 extend is folded in plaits like a fan, after which the wing is folded 

 twice crosswise. This part of the wing is the greatly expanded anal 



Fig. 539. — Hind wing of an earwig: nf, nodal furrow. 



area. The preanal area is much reduced and contains only two 

 longitudinal veins ; this area is quite densely chi tinized. The trachea- 

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

 (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. 



