172 The Orders of Insects 



at the last moult are transformed into the forceps. Ear- 

 wigs pass much of their time under stones and in other 

 concealed situations; their flattened bodies enable them 

 to retire into small crevices. They feed on various 

 vegetable substances — flowers, fruit, and leaves ; but, 

 at times, they attack and devour other insects. 



The order Dermaptera contains but a single family,^ 

 the Forficulid<e , in which some 400 known species 

 are comprised, distributed among numerous genera 

 (3, 104 a, 105). Earwigs are most numerous in the 

 tropics, but they are represented in all parts of the 

 world. ^ 



ORDER 4.— ORTHOPTERA. 



Structure. — In this Order, several families of 

 insects are included which differ considerably in the 

 details of their structure. All agree, however, in the 

 possession of biting jaws, like those of the Cockroach, 

 the second pair of maxillge being incompletely fused 

 together. The three thoracic segments are easily 

 distinguishable. There are ten evident segments in 

 the hind-body, the last bearing a pair of cercopods. 

 The wings are characteristic in form, the front pair 

 being of firm texture and serving as covers for the 

 more delicate hind pair which can be folded fan-wise 

 beneath them. The neuration in both fore and 

 hindwings is complex. Four principal longitudinal 

 nervures can be recognised on each forewing — the 

 sub-costal ^ near the costa, the radial, the median, and 

 the anal ^ — in the hindwings there is also an ulnar 

 nervure, between the radial and median. From the 

 principal nervures branches arise, and a number of 

 short cross nervules connect these. The anal area, be- 



^ Unless the Hemimerids (see below under Orthoptera) should 

 be included in this order. 



- Or mediastinal. ^ Or dividens. 



