126 THE CAUSES WHICH PROPAGATE 



US to a lima and clasp. And it is further certain that a 

 note quite similar to that of the moth results either from 

 simply expandinp^ the fore-wing-s, when the elbow at the base 

 (Plate IV., Fig-. 3, /) leaves the indented edge of the lateral 

 and dorsal piece of the metathorax {a), round which it 

 clasps in the posture of repose, with a frictional sound, or from 

 chafing this elbow backwards and forwards over the hinder wing 

 surface. On submitting these parts to a high magnifying 

 power, I find the callosity (.'3, b), which in many moths locks 

 the forewings to the body, unusually developed, obliquely 

 striated, and placed at the inner edge of the elbow, while the 

 sub-costal nervure of the hind wing is raised to form a catch, 

 and minutely indented. When stridulating it has been observed 

 to inflate the abdomen and protrude a filament (fan ?) . 



One of the Tortricina (Plate IV., Fig. 2) shows a propensity 

 to stridulate. It was, I remember, one sunny afternoon I went 

 to pay a call at East Cowes, in the Isle of Wight. The lawn 

 was being mowed. My attention was attracted by a little ring 

 of male Bicroraiiipha sequana, paying respects to a female at the 

 eJge of the long flowering grass. They flew around her, chased 

 each other, and went through various antics, always retiring 

 settling on grass-stalks in the immediate vicinity. But what 

 surprised me most was to see one exasperated little atom sud- 

 denly raise its two fore-wings perpendicularly, and pass them 

 rapidly over the front edge of the two hinder. 



When the little society was on the point of dispersing, I 

 managed to pill-box a few, and subsequently submitted them 

 to a magnifying power to see if any trace of a file and clasp Avas 

 to be found to account for the strange proceeding witnessed. All 

 I have to say is, that, finding the front edge of the hind wing of 

 one a little rubbed, I denuded it, and then discovered it furrowed 

 perpendicularly to the edge, but whether this be sufficient to 

 enrol this diminutive creature as a stridulator or not, I must 

 leave to future observers. 



Lastly, with regard to the Tinea, I would call attention to 

 page 362 of the second volume of " Stainton's Manual,^^ where 

 it is stated : — " The species of the genus Glyphipteryx have a 

 peculiar habit of slightly raising and then depressing their wings, 

 as though fanning themselves ; and G. Thrasonella, which is 



