LIGHTNING-BUGS. 57 



then in the larva, there appearing like little sacs on the under 

 surface, one on each side of the middle line, so arranged that 

 the insect can hide them by retracting the body, and causing 

 them to blaze out when the abdomen is extended. Nothing 

 in all nature is more wonderful than the changes through 

 which these and other insects pass before attaining adult 

 growth. 



The larva is a busy little creature, full of life ; but, when 

 about to change, it becomes lethargic and quiet, as it im- 

 pressed with the importance of the coming metamorphosis. 

 Finally it wriggles out of its old skin, and becomes a pupa, 

 also luminous ; exceedingly lively, yet with its motions 

 restricted. It moves its antennae and legs, and pushes itself 

 along by movements of the abdomen. Finally the perfect 

 insect appears, with its wondrous array of lights, so little 

 understood, and which, if accompanied with the ordinary 

 amount of heat attendant upon such a display, would soon 

 roast or fry its possessor. As to the use of the lights, we can 

 only conjecture. It has been shown that one insect recog- 

 nized the other by it, and thus it may be a sign language ; 

 while, according to others, it is a warning to birds and other 

 enemies. 



Mr. Darwin thus refers to the lightning-bug of South 

 America: "All the fire-flies which I caught here (at Rio) 

 belonged to the Lampyridce (in which family the English 

 glow-worm is included), and the greater number of speci- 

 mens were of Lampyris occidentalis. I found that this insect 

 emitted the most brilliant flashes when irritated; in the 

 intervals, the abdominal rings were obscured. The flash 

 was almost co-instantaneous in the two rings, but it was just 

 perceptible first in the anterior one. The shining matter 



