232 OUR INSECT FRIENDS AND FOES 



oval spots on the upper surface of the first ring 

 of the thorax, and another even more brilliantly 

 luminous organ is situated on the first ring of 

 the abdomen. These light-producing organs 

 are special modifications of the epidermic cells, 

 disposed in two layers, of which the outer one 

 appears to be alone luminous, while the inner 

 one contains masses of waste products, and is 

 pierced by innumerable air-tubes (trachea). 

 The luminosity of these organs depends on a 

 process of oxidation, the oxygen being supplied 

 by the trachea, the brilliancy of the light 

 varying with the respiratory activity of the 

 insect, nervous stimulus having little or no 

 effect upon it. Although the subject has 

 engaged the attention of many eminent 

 chemists and physiologists, what the substance 

 oxidized really is still remains undiscovered. 

 The Indians make considerable use of these 

 beetles, attaching them to their hands and feet 

 when travelling through the forest at night. 

 They attract the beetles by means of glowing 

 coals or other form of light on the end of sticks 

 which are gently waved about, and capture them 

 in nets. The beetles so collected are carefully 

 tended, kept in boxes covered with fine wire 

 gauze, bathed twice daily in tepid water, and 

 fed with pieces of sugar-cane. The beautiful 

 Brazilian and Creole women make use of these 

 Fireflies, or cucujos, fastening them in little 

 transparent bags of light tulle to their dresses 

 and hair ; the effect produced by the tasteful 

 grouping of these living jewels being parti- 

 cularly striking and beautiful. 



