200 ORTHOPTERA chap. 



for flight, and are in some cases devoted to what we may call 

 purposes of ornament or concealment. This is specially the case 

 in the Phasmidae and Mantidae, where the effectiveness of colour 

 and pattern of these parts becomes truly astonishing. The 

 tegmina frequently exhibit an extraordinary resemblance to 

 vegetable structures, and this appearance is not superficial, for it 

 may be seen that the nervures of the wings in their disposition and 

 appearance resemble almost exactly the ribs of leaves. One of the 

 most remarkable of the features of Orthoptera is that a great 

 difference frequently exists l^etween the colours of the tegmina 

 and of the wings, i.e. the front and hind wings ; the latter are 

 concealed in the condition of repose, but when activity is entered 

 on and they are displayed, the individual becomes in appearance 

 a totally different creature. In some cases, contrary to what 

 usually occurs in Insects, it is the female that is most remark- 

 able ; the male in Mantidae and Phasmidae being frequently a 

 creature of quite inferior appearance and power in comparison 

 with his consort. The musical powers of the saltatorial 

 Orthoptera are, however, specially characteristic of the male sex. 

 There is evidence that these powers are of great importance to 

 the creatures, though in what way is far from clear. Some parts 

 of the structures of the body are in many of these musical species 

 clearly dominated by the musical organs, and are apparently 



specially directed to 

 securing their effici- 

 ency. We find in some 

 Locustidae that the 

 tegmina are nothing 

 but sound - producing 

 instruments, while the 

 pronotum is prolonged 



Fig. 101. — PoeciUinon affinis S . Bulgaria. Alar organs to form a hood that 

 serving only as musical organs. The ear on front ,, 4.^ 4. ^i wi'l-limit 



tihia and aural orifice of prothora.x are well shown. P^Ol^ectiS tnem WltftOUt 



encumbering their ac- 

 tion. In the males of the Pneumorides, where the phonetic organ 

 is situated on the abdomen, this part of the body is inflated and 

 tense, no doubt with the result of increasing the volume and quality 

 of the sound. In the genus Metlione (Fig. 185) we find a grass- 

 hopper whose great hind legs have no saltatorial function, and but 

 little power of locomotion, but act as parts of a sound-producino- 



