96 BUTTERFLY SOUNDS 



extremities, so placed that when the fore wing is 

 moved up and down they play upon a pair of some- 

 what similar processes attached to the tliorax ; 

 these being abruptly released from contact when 

 the wing reaches a certain angle, would be likely 

 to produce a snapping sound or " click." 



Many observers have noted the j)eculiar move- 

 ments of the wings of butterflies which are not 

 accompanied by audible sounds, especially in the 

 family Lycaenidae, where the hinder wings alone, 

 erect when the insect is at rest, are rubbed to- 

 gether in a curious way, giving them " the appear- 

 ance of revolving disks," as Mr. Wallace calls it ; 

 and many observers have attempted to discover 

 whether any sound followed this motion, but none 

 have succeeded in doing so. Yet any other expla- 

 nation of the intent of the movement would seem 

 to be almost out of place, inasmuch as it is invari- 

 ably made by certain species, including many of 

 our own native kinds, directly uj)on alighting, and 

 at a time when there may well be no butterflies in 

 sight. 



This movement of the hind wings has been 

 repeatedly seen and remarked upon by observers 

 in all parts of the world. Swinton thought he had 

 found the source of the possible sound that may 



