150 A NATURALIST IN BORNEO 



Certain species of Phasmids are bulky creatures, and 

 are protected by an elaborate armature of stout and 

 sharp spines which renders them very unpleasant to 

 handle, especially as they struggle valiantly when 

 captured, scraping their spiny legs against the hands and 

 fingers of the ardent entomologist. The male of one of 

 the spiniest species, Heteropteryx grayi [Note 12, p. 315], 

 has the power of stridulating quite loudly when irritated, 

 by scraping the wings against the under-side of the wing- 

 covers. The wing-covers and wings are reduced rudi- 

 mentary organs in the male sex of this genus, and are 

 quite useless for purposes of flight ; their function of 

 producing a hissing sound is a secondary modification. 

 The veins on both wings and wing-covers are very 

 strongly developed and stand up as ridges ; the wing- 

 covers are incapable of independent movement and lie 

 as mere flaps over the short wings ; but these latter 

 organs can be moved, and when the insect is irritated 

 they are quickly raised up and down, lifting up the 

 passive wing-covers and scraping against their under- 

 surface with each movement. A good many Phasmidce 

 with larger wings, though scarcely large enough to 

 serve usefully in flight, make a rustling sound by re- 

 peatedly opening and closing the wings, and this they 

 do when irritated. A Brazilian species, Pterinoxylus 

 difformipes, has in the female a stridulating apparatus 

 something like that of the male Heteropteryx. The fore 

 margin of the rudimentary wings is finely shagreened, 

 and when the wing is raised this margin scrapes 

 against the edge of the wing-covers. There is a large 

 clear patch on the disc of the wings like a speculum, 

 and it has been suggested that this is thrown into 

 vibrations by the scraping of the wings against the 



