Patricia Rodgers, age 11, of Wagener, S.C.., for her question:

How does a 1ightning bug light?

This is one of Andy's most popular summer questions and this year it was asked by very many readers. If you were one of them, please do not feel sad or mad because Andy selected Patricia's question. If you were smart enough to ask one good question, you are smart enough to ask many more, And you can have as many tries as there are fireflies over all the meadows and gardens of all of North America.

Some people call them lightning bugs, some call them fireflies and some c4ll them lightning beetles. The last is more correct, for these little fairy sparklers are neither flies nor bugs in the true sense. They belong to the beetle order of the insect clan. Some of them flash their lights in flight, some glow as wormy larvae and the wingless glowworms of Europe never take to the air.

There is much that is still mysterious about the fireflyts magic spark, though scientists are working hard to reveal the secret. The secret is worth knowing, for the firefly and certain other animals and plants can make light without heat. All our lights, from candles to flood lights waste a lot of energy by giving forth heat along with their light. The study of this heatless light is called bioluminescence.

Bioluminescence in the firefly involves a number of chemicals with some rather fancy names. The tiny insect uses the chemicals lucilerin and luciferase, adenosine and triphosphate, magnesium and ,just plain oxygen. A magic brew of these chemicals is present in the fatty tissue of the fireflyts abdomen. Also present in this tissue is a chemical called pyrophosphate. A nerve impulse triggers off a reaction between these chemicals and, for a few seconds, the little insect flashes on and off his fairy light.

The triggering action releases the chemical pyrophosphate which breaks up the bond or mixture of the first five chemicals. As this chemical bond, or bundle, breaks apart, light is given off. The firefly glows like a small fairy lantern. But only for a second or so. Then the pyrophosphate is destroyed and the cycle starts all over again.

This evening, the fireflies will be glowing and glimmering over the gardens and meadows of most of North America. Sad to say, these fairy creatures do not add their fairy sparks to California, for we do not find many of them west of the Rockies. In the tropics there are fireflies several inches long. They are so lovely that girls wind them into their hair as ornaments.