The Nature Writers of Texas

The best nature writing from the newspaper, magazine, blog and book authors of the Lone Star State . . .

Sunday, May 20, 2007

Fireflies, Nature's Evening Sparklers, Light Up the Night
by Ro Wauer

Every spring I am amazed all over again when the yard is suddenly filled with glowing lights from fireflies! I can't help but get excited for the umpteenth time about this marvelous work of nature. What child has not shared that amazement? Who has not captured one of these fascinating insects to watch it glow up close? Who has not wondered about these tiny creatures that turn our yards into miniature firefights?

The appearance of fireflies, sometimes known as "lightning bugs," are a sure sign that the winter months are behind us and summer is not far off. Fireflies appear only when the evening temperatures allow these cold-blooded insects, actually a soft-winged beetle of the Lampyridae family, to become active. The majority of the 2,000-plus members of the Lampyridae family (there are about 60 kinds in North America) possess luminous organs on their abdomens. They all are able to glow at will, usually starting at dusk and continuing until about midnight, generally as part of courtship to attract a mate.

Our fireflies are most numerous in humid yards and similar locations. The male firefly beetle is about 1/2 to 3/4 inch in length, with a pair of fairly long antennae and a yellowish abdomen. Females look more like larvae than beetles. Although both sexes glow, males are capable of shining about twice as bright as the females.

Each of the more than 2,000 forms of fireflies possesses a slightly different glow pattern or code of signals. The specific code is not so much the light (either color, brilliancy, or length) as it is the length of the intervals. Each species glows for a specific length of time, with a specific interval between glows. The males of some tropical fireflies actually flash in unison, and the tropical nights can actually brighten as if a great light is turned on and off. You can experiment with a penlight by copying the glow intervals to solicit a response.

The light itself is derived from the fatty tissue, called "luciferin," in the beetle's abdomen. The light is produced when the insect takes in air through tiny ducts. When the air reaches the luciferin, it is instantly oxidized, releasing the energy as cold light.

During the daytime, the lampyrid beetles and their larvae are usually found on vegetation where they prey on smaller insects and larvae, small arthropods, and snails that they find on old leaves or humus, or on the ground. But at dusk, the males begin their nocturnal signals, flashing their unique lights in such a way that their mates are soon flashing back. And the night becomes magical!

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