THE MOTHS' DANCE 



more stationary on the wing than the male, the 

 whirr of her wings being more intense. Even so, 

 the vibration of the wing of the ghost moth when 

 she swings to and fro and hovers is, I think, less 

 than that of the humming-bird hawk moth, or 

 the common gamma, now seen shaping a lightning 

 course from one disk of the honest smelling elder 

 bush to another. 



On this subject I have just had an interesting letter 

 from Mr. W. H. Hudson, a naturalist finished to the 

 finger-tips. He writes: "When the moth is swinging 

 to and fro, one effect is produced or so it seemed 

 to me which you do not notice. The wings are 

 not so rapidly vibrated as in most moths, so that 

 they do not appear as a semicircle of mists ; they 

 are seen as wings still, only multiplied, as if the 

 moth had four or six wings on each side." This 

 is a pretty and true observation, I think. When 

 the common gamma or the humming-bird hawk 

 moth is whirring, the beat of the wings is so 

 intense that you cannot distinguish their outlines. 

 Similar effects are seen in the revolution of the 

 electric air fan employed in crowded public rooms, 

 and in the hover of the kestrel only the kestrel's 

 wings at a considerable distance appear fixed and 

 motionless. The hover of the ghost moth in its 

 dances is not, of course, to be confounded with the 

 other wild and irregular stroke of the wing which 

 he makes in moving to a fresh place. 



The female ghost moth, like the male, is, I fancy, 

 soon exhausted by the frenzy of the exercise. I saw 



