LUMINOUS INSECTS. 



331 



evenings which an English summer seldom yields, when not a 

 breeze disturbs the balmy air, and " every sense is joy," and 

 hundreds of these radiant worms, studding their mossy couch 

 with mild effulgence, were presented to your wondering eye 

 in the course of a quarter of a mile, — you could not help as- 

 sociating with the name of glow-worm the most pleasing re- 

 collections. No wonder that an insect, which chiefly exhibits 

 itself on occasions so interesting, and whose economy is so re- 

 markable, should have afforded exquisite images and illustra- 

 tions to those poets who have cultivated Natural History. 



If you take one of these glow-worms home with you for 

 examination, you will find that in shape it somewhat resembles 

 a caterpillar, only that it is much more depressed ; and you 

 will observe that the light proceeds from a pale-coloured patch 

 that terminates the under side of the abdomen. It is not, 

 however, the larva of an insect, but the perfect female of a 

 winged beetle, from which it is altogether so different that 

 nothing but actual observation could have inferred the fact of 

 their being the sexes of the same insect. In the course of our 

 inquiries you will find that sexual differences even more ex- 

 traordinary exist in the insect world. 



It has been supposed by many that the males of the dif- 

 ferent species of Lampyris do not posses the property of giving 

 out any light ; but it is now ascertained that this supposition 

 is inaccurate, though their light is much less vivid than that 

 of the female. Ray first pointed out this fact with respect to 

 L. noctiluca 1 , which has two luminous points on the penul- 

 timate abdominal segment. In the males of L. splendidida 

 and of L. hemiptera the light is very distinct, and may be seen 

 in the former while flying. 2 The females, like the males, 

 have the same faculty of extinguishing or concealing their 

 light — a very necessary provision to guard them from the 

 attacks of nocturnal birds ; Mr. White even thinks that they 

 regularly put it out between eleven and twelve every night 3 : 

 and they have also the power of rendering it for a while more 

 vivid than ordinary. 



Authors who have noticed the luminous parts of the 



i Hist. Ins. 81. 



3 Nat. Hist. ii. 279. 



2 Illiger, Mag. iv. 195. 



