THE BEAUTY OF THE NIGHT 359 



monest species is probably one of wide range in 

 the United States (Photinus ardens), being found 

 as far north as Indiana. In its case both names 

 are very appropriate. "Photinus" means shin- 

 ing and "ardens" to glow or burn, so this little 

 insect gets a good advertisement with each name. 

 It is a slender, brown beetle, the elytra or wing 

 covers being bordered with dull buff and the 

 shield of the thorax extends forward so that look- 

 ing at it from above the head is entirely Covered 

 as by an umbrella. The light-giving apparatus is 

 located in two segments of the abdomen and is 

 composed of fatty tissue, which is burnt without 

 sensible heat, at the time of showing the light, the 

 process being -controlled by the will of the insect. 

 In the male the light organs are more strongly 

 developed than in the female, and the larvae, which 

 are found in damp places, also emit a feeble light. 

 Kirby and Spence believed that this light is used 

 to frighten enemies and others claim that it is a 

 sex signal or perhaps displayed in rivahy among 

 the males, but we probably do not understand its 

 full significance. 



In this species the flare is often slightly greenish 

 but sometimes it is red or yellowish, varying some- 



