Beloved, whether fireflies or lightning bugs

Published 10:08 pm Tuesday, June 13, 2017

By Susan and Biff Andrews

For kids — and former kids, too — summer means lightning bugs. Fireflies.

You know the drill, get the Mason jar; jab holes in the lid; put in some sticks, grass and leaves; and then just add bugs.

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Catch them by hand or with a butterfly net or pick them off screens or bushes, usually just at twilight. Fill the jar. Marvel at them in the total darkness and then release them all, either that night or first thing in the morning.

Magical! A magical rite of passage.

But with adulthood come questions, which require answers, through research.

First of all, they’re not flies; they’re beetles. They are Lampyridae, winged beetles.

It’s ironic that they’re called “fireflies,” because the light they emit through bioluminescence is cold light. There is no infrared, no ultraviolet heat at all. They’re 100-percent efficient, not like light bulbs, which are 10 percent light and 90 percent heat.

There are about 2,000 species. Some are lightless, as in California. Some are aquatic — at least the larvae. Some females are wingless and therefore flightless.

Most fireflies live in moist wooded areas. Some larvae emit light underground and are called glowworms in Eurasia, but not here.

Firefly eggs are laid just below the surface of the ground. Eggs hatch in about 3 weeks, and the larvae feed until the end of summer. Then they hibernate until spring. They feed a while on slugs, worms and snail larvae. Then they pupate for a couple of weeks, and then they hatch into adults.

Light production on a firefly’s lower abdomen involves luciferase, luciferin, magnesium and oxygen. The light in adults is a warning sign to predators that they taste awful, and it’s a way to attract a mate.

There are many reasons why lightning bugs are in decline — light pollution, habitat loss and pesticides.

Concerning the habitat loss, apparently if a riverfront field is paved over, the lightning bugs don’t move to another field, they just cease to exist. Pesticide effects go without saying. And one can only imagine a lightning bug’s dismay at encountering the light pollution of powerful streetlights.

Whether or not you’re a ”naturalist,” as we are — whether you’re a tree hugger or not, surely you want your children, your grandchildren, your grandchildren’s children to have the firefly experience: Prepare the jar, catch the lightning, let them all go as a way to teach mercy to God’s creatures.

So we leave leaf litter in parts of the yard. We turn off outdoor lights at night. And we protect our habitat by not using pesticides.

Every little bit helps.

Susan and Bradford “Biff” Andrews are retired teachers and master naturalists who have been outdoor people all their lives, exploring and enjoying the woods, swamps, rivers and beaches throughout the region for many years. Email them at