Randy Tufts, age 8, of Tucson, Arizona, for his question:

What is the secret of the firefly?

So far, the little firefly has kept his secret to himself. We know where he makes his magic light and what he uses to make it. But the details of how he does it are still a mystery. Experts have tried hard to discover the firefly's secret because we would like to copy it. His glow is a very special kind of light. All our lamplight ‑ candle, kerosene, gas and electricity ‑ has a certain amount of heat. We do not need heat with our light and it is merely wasted energy. The firefly, and only the firefly, knows how to make light without heat.

The fat little fellow is easy to catch. You can hold him in your cupped hands or put him gently into a glass jar. The roly poly little beetle will keep flashing his light on and off for you. Watch where it happens. He seems to have a minute light bulb in the tail end of his soft, segmented tummy. That is where he has his light‑making factory.

Thu, little generator is made of fatty tissues riddled with tiny tubes and tunnels, Also present is a fuel called luciferin and enzyme called luciferase. Both of these names are coined from an old word for light. The fuel luciferin uses oxygen. The enzyme luciferase orders the magic process to work without doing any work itself.

The firefly's light is like an ordinary fire in that it uses up oxygen. It differs in that the fuel luciferin is not burned away. The firefly is able to have his light and keep his fuel. For, in the lighting process, the luciferin reacts with oxygen and is then changed back into fuel luciferin ‑again. And we are still trying to find out how this economical trick is done.

The lightening bug or firefly is really neither a bug nor a fly. He is a beetle of the Lampyridae family of insects. Fifty different varieties live in North America. In some cases the caterpillars and even their eggs can glow with ti firefly light. We may spot their little lamps on mossy ground or in damp grasses.

The true glow worm is a grownup beetle. She is a lady firefly without wings though she looks like a lamplit caterpillar. The lightening bug, flashing on and off as he circles over her head, is not her husband. He is a cousin firefly. The husband of the glowworm traded his light for a pair of wings.

There is a fine article on fireflies and glowworms together with pictures in your gift encyclopedia. The fairylike beetles are all meat eaters dining on insects, snails and whatever small gamy; they can find. Most experts say that the flashing lights are courtship signals ‑ gay little winks between girl fireflies and boy fireflies. They may also serve to scare off hungry birds. For the fairy bottle has a nasty flavor and a bird who has eaten one will avoid those blinking lights in the future;.