84 WOODLANDERS AND FIELD FOLK 



the British Lepidoptera; and each time the strange 

 sound is emitted, the whole body gives a convulsive 

 movement. The insect can be induced to utter this 

 strange note by being irritated. 



Another specially interesting night-flyer is the 

 ghost moth. Just as the twilight of a summer 

 evening is deepening into darkness, and a soft, warm 

 wind stirs the foliage of the woods, the ghost moth 

 comes abroad. The observer sees a fitful apparition 

 which suddenly vanishes into space. A large insect 

 with long wings is seen advancing; it comes straight 

 on, then flutters in the air, and is gone. Whilst 

 endeavouring to discover the mysterious retreat 

 of the moth, it will suddenly reappear, and, even 

 whilst the eye closely follows its flight, will again 

 vanish. This effect is produced by the different 

 colour of the wings on their upper and lower sides. 

 Above they are snowy white, and consequently 

 visible even in the deep twilight; but on the under 

 side they, as well as the whole body, are of a deep 

 dusky brown so that when that side is suddenly 

 turned towards the spectator it becomes invisible. 

 As the male flies in the night, the white shining 

 upper surface of the wings glitters curiously, so that 

 they almost appear as if they were giving out their 

 own light 



