Insect Study 417 



microscope, prove to be filled with fine tracheae, or air-tubes ; and although 

 we know very little about the way the light is made, it is believed that by 

 flooding the tubes with air, the oxygen in some way produces the 

 light. 



In some species, the female is wingless and has very short wing- 

 covers, and a portion of her body emits a steady, greenish light which tells 

 her lord and master where to find her. These wingless females are called 

 glow-worms. 



Fireflies during their larval stages are popularly called wire worms, 

 although there are many other beetle larvae thus called. In many of the 

 species, the firefly eggs, larvae and pupae are all luminescent, but not so 

 brilliant as when adults. The larva of the species here figured, was 

 studied by C. V. Riley, who gave us an interesting account of its habits. 



It lives in the ground and feeds on soft-bodied 

 insects, probably earth-worms. Each segment of this 

 wire worm has a horny, brown plate above, with a 

 straight white line running through the middle and 

 a slightly curved white line on each side ; the sides 

 of the larva are soft and rose-colored; the white 

 spiracles show against little, oval, brown patches. 

 Beneath, the larva is cream color with two brown 

 comma-like dots at the center of each segment. 

 The head can be pulled back completely beneath the 

 first segment. The most interesting thing about this 

 larva is the prop-leg at the end of its body, which 

 naturally aids it in locomotion ; but this prop-leg also 

 functions as a brush; after the larva has become 

 After c. v. Riley. soiled with too eager delving into the tissues of some 

 earthworm, it curls its body over, and with this fan- 

 shaped hind foot scrubs its head and face very clean. This is a rare 

 instance of a larva paying any attention to its toilet. 



When full-grown, the larva makes a little oval cell within the earth and 

 changes to a pupa ; after about ten days, the pupa skin is shed and the 

 full-fledged beetle comes forth. The larva and pupa of this species give 

 off light, but are not so brilliant as the adult. The pupil should be en- 

 couraged to study the early stages of the fireflies, because very little is 

 known concerning them. 



In Cuba a large beetle called the cucujo has two great oval spots on its 

 thorax, resembling eyes, which give off light. The Cuban ladies wear 

 cucujos at the opera, in nets, in the hair. I once had a pair which I 

 tethered with gold chains to the bodice of my ball gown. The eye-spots 

 glowed steadily, but with the movement of dancing, they grew more bril- 

 liant until no glittering diamonds could compete with their glow. 



LESSON XCIV 



THE FIREFLY 



Leading thought When the firefly wishes to make a light, it can pro- 

 duce one that, if we knew how r to make, would greatly reduce the price of 

 electric lighting; for the light made by fireflies and other creatures, 

 requires less energy than any other light known. 



Method After the outdoor observations have been made, collect some 

 of these beetles in the evening with a sweep net; place them under a 



