Light In Flight

For a detailed look at these de-light-ful creatures, read chapter seven of Discover Nature at Sundown: Things To Know and Things To Do, by Elizabeth P. Lawlor, Stackpole Books, $14.95. This excellent book suggests a number of observation activities related to fireflies and other nocturnal beings.

Fireflies in the Night, by Judy Hawes (Crowell Co.) provides a good explanation geared to children ages 4-8. The revised edition was first published in 1963 and is part of the "Let's Read and Find Out" series.

Be sure not to miss Eric Carle's The Very Lonely Firefly, the gentle tale of a firefly in search of companions. At the end of this classic Carle book, tiny bulbs embedded in the book light up, just like a group of fireflies. The story is available in both board book and hardcover format.

Another fun choice is Sam and the Firefly, by Philip D. Eastman, an easy reader for ages 4-8, Random House. Sam, an owl, teaches Gus, a firefly, to write words with his light. The fun starts when Gus writes his own mischievous messages.

Mysteries Explained
Fireflies provide a great opportunity to give your kids a science lesson.

Fireflies are actually members of the beetle family. Technically, they're part of the family Lampyridae, order Coleoptera. Scientists estimate there are about 2,000 named species of fireflies, with more being discovered. About 200 of these species live in North America, so you've got great chances of seeing them.

The light they shine is a phenomenon known as bioluminescence, or "living light." It's often referred to as "cold light," as opposed to the light produced by an incandescent light bulb, for instance, in which much of the energy (97 percent) becomes heat.

Here's the technical bit: The light is produced when oxygen combines with a substance called luciferin in the presence of luciferase, an enzyme.

Fireflies aren't the only bioluminescent organisms. Certain other beetles, gnats, bacteria, fish, fungi, jellyfish, sponge and worms are among those critters that also produce the effect. Yet another example is foxfire, the glow produced by luminescent fungi on decaying wood.

So why do fireflies glow? In most species, female fireflies "flash" to signal to males that they're ready to mate. Each sex of each species has its own "flash code" so that kindred species will find each other.