THE NIGHT SIDE OF NATURE 95 



the light of the glow-worm is in the tail, and proceeds 

 from three luminous sacs in the last segment of the 

 abdomen. The male has only two of these, and the 

 light proceeding from them is comparatively small. 

 During favourable weather the light glows steadily, 

 but at other times it is not constant. The fireflies of 

 the Tropics those comprising the genus Lampyridce 

 vary to the extent that while certain species 

 control their light, others are without this power. 

 The light of our English glow-worm is undoubtedly 

 under its control, as upon handling the insect it is 

 immediately put out. It seems to take some little 

 muscular effort to produce the luminosity, as I have 

 observed an insect move continually the last segment 

 of the body so long as it continued to shine. The 

 larvae of the glow-worm is capable of emitting light, 

 but not to be compared to that of the developed 

 insect. 



Both in its mature and immature forms, Lampyris 

 noctiluca plays a useful part in the economy of 

 Nature. To the agriculturist and fruit-grower it is 

 a special friend. Its diet consists almost wholly 

 of small shelled snails, and it comes upon the scene 

 just as these farm and garden pests are most trouble- 

 some. British fireflies probably have never yet 

 figured as personal ornaments to female beauty. 

 This is, and has always been, one of their uses to the 

 dusky daughters of the Tropics. They are often 



