174 THE CAUSES WHICH PROPAGATE 



this angry turmoil is heard to surge and drive along the ground, 

 as the prattling of a hasty shower^ or the wind caught in the 

 aspen. This is a sure token a male is advancing to one of the 

 females : he does so delicately or persuasively, with a pre- 

 meditative feint at stridulation, vibrating the hind legs for a 

 time, and eventually raising a faint sound, an overture never- 

 theless understood, and immediately chorused from all sides. 

 The would-be suitor patiently receives the general ovation with 

 a listening leg wakefully lowered, and then sliarj)ly gives his 

 response by jerking the right femur forwards on the wing- 

 covers, with a sound of '^ Tir]3 ! tirji ! " the proper call-note. 

 He also, as the fit takes him, leaps on the female, bites her, 

 and moves one of his legs from one to five times forwards, 

 when the note runs to a species of cackle. The males also 

 dash at one another ; and when wearied with their solicitations, 

 or annoyed at a bite, the portly female leaps off, one or the 

 other follows on her bounds, and endeavours to arrest her Avith a 

 twang on his violin. When united, the note is softly mitigated 

 to a low squeak, '^ Weha ! " 



Regarding the notation of the ordinary challenge-note of 

 the Variable Grasshopper some confusion prevails. Fischer says 

 that the male, when stridulating, rubs the femora simultaneously 

 against the elytra, and gives out a powerful song, now and 

 again rising with a metallic accent, and then decreasing. This 

 sound may be imitated with the breath ; but those males who 

 have the anterior area of their wing-covers less dilated stridu- 

 late more gently. Yersin merely gives the notation he before 

 attributes to the Red-legged Grasshopper, and adds, the stridor 

 consists of from one to three notes. He likewise notices that 

 when the female is present the legs vibrate before the note is 

 heard, and then it arises shorter and softer. He next proceeds 

 to give his studies of the music of two varieties, which in his 

 time were considered distinct species. The greenish sport Char- 

 pentier, in his " Horse Entomologicae,'' terms mollis, he says has 

 a music composed of from twenty to thirty notes, with in- 

 creasing intensity, the former lasting less than half a second, 

 and more acute than the latter, which besides are much slower, 

 so that it even happens that the eight or ten concluding sounds 

 attain each nearly a second^s duration. As regards other 



