Lights of a summer night

On a warm August evening, stretched out in wicker chairs across a porch, everybody is trying to remember which stars belong to the Little Dipper, way up there, when suddently out of the blackness another sort of constellation appears: those first-magnitude stars on earth -- fireflies. No memory of childhood remains more vivid.

Is there any summertime sight more mysterious, and more heart-stirring, than the pulsing glow of photinus pyralis?m Entomologists -- for the firefly is, in fact, a beetle -- tell us the light gets triggered in the lower abdomen. The firefly's signal has as much as one-fiftieth the power of a candle, yet the ratio of heat is one to 80,000. There are more spectacular illuminators in nature than the firefly. For instance, the South American glowworm boasts a red light on its head and row of greenish lights on its sides, earning it the nickname of "railroad worm." But no light in this world is cooler than the light of the firefly, and this cool fire -- this nonconsuming fire -- fascinates us children of Prometheus.

Scientists at Johns Hopkins and elsewhere have been trying to understand how the fireflies do it, blinking like tiny synchronized lighthouses in the night. The process can be partially described in terms of oxygen and enzymes, but the why escapes.

What does it all mean, this deviceful attention-getting of the firefly? -- played out to rhythms as precise as a string sector under Arturo Toscanini. In the first place, we do know that when, say, a two-second interval occurs between flash and flashback, then a courting through light-language is taking place -- a sort of wooing by firefly's Morse code.

Still, no purpose has been discovered for the popular and massive winking and blinking of male fireflies in groups. In southeast Asia fireflies congregate by the tens of thousands on the leaves of trees to throw light along a swathe of several hundred yards. They may continue for weeks, night after night, dousing their lights only when the moon becomes extraordinarily bright.

Why?

Civilization began with fire, with light. The firefly watcher is anciently trained to respond to light as to a signal. Light is hope to the hopeless, direction to the lost. Light is the promise of a hearth in the middle of a dark forest. Light tells the lonely and the terrified: You are not alone.

It is not fashionable to assume that nature operates for the express benefit of humans, but who, seeing fireflies on an August evening, can help thinking that an interspecies message is being sent, if only we non- fireflies had the wit to decode it?

According to American folklore, an encounter with fireflies my presage some success just as sparkling to follow. The Japanese have associated the firefly with diligent work -- lighting the pages of sleepless students throughout long hot nights.

Do we read into the light of the firefly, as societies, as individuals, what we choose to read? So be it. For the moment myths are the only explanations we really have.

"Of what use is all the pyrotechnic display? asked the great French naturalist Jean Henri Fabre, applying the question to all luminous insects. "To my great regret, I cannot tell. It is and will be, for many a day to come, perhaps for all time the secret of animal physics, which is deeper than the physics of books."

But on an August evening, as the lights exultingly flare out of the darkness, we must imagine that a great cosmic party is going on -- and, as certainly as the signal from sparklers on the Fourth of July, we too are being invited to celebrate.