The female glow worm is equipped with a marvelous lighting system. A wingless beetle, she crawls about at night eating small insects. On the lower side of her abdomen she posesses a "lantern" which she uses to signal to her winged mate flying above. This "lantern" has a transparent layer of skin. Behind this is an oily layer of tissue which chemically produces the light, and a second layer which acts as a reflector.
The glow worm is able to control this remarkably bright light, using it only at certain times to attract a mate. The male is equipped with particularly large eyes to enable him to see the signal. An abundant supply of oxygen and water is needed by the glow worn to maintain the chemical activity that produces the light. For a time, even the insect's eggs are luminous.
Glow worms, which are about half an inch long, are natives of Europe.