Sorry, you need to enable JavaScript to visit this website.
Article Image Alt Text
  • Article Image Alt Text
  • Article Image Alt Text
  • Article Image Alt Text
    The light from the chemical reaction in fireflies is called “cold light,” because it doesn’t produce any heat.
  • Article Image Alt Text
    A firefly on a blade of grass at dusk, getting ready to fly into trees and signal for a mate.
  • Article Image Alt Text
    Most of us have childhood memories of fireflies in a jar.
  • Article Image Alt Text
    A summer field full of fireflies.

Drippin’ Gardening

Where have all the fireflies gone?

Do you miss those warm summer evenings lighted intermittently by the little flashes of fireflies? Many of us have been fortunate enough to enjoy the magic of fireflies but it is a privilege that our children and grandchildren may be denied. That is sad.

Call them fireflies, lightning bugs, or glowworms, one thing you can’t call them (in recent years) is plentiful. You can still find the flashy bugs in many areas of the country, but in Texas you might have to do some serious searching, report two Texas A&M University researchers. Entomologists Ed Riley and Bart Drees say the past few years have dimmed the lights of the flashy insects dramatically.

Like Fourth-of-July fireworks, tubing on the San Marcos River, and lazy vacations, fireflies are a sign of summer. Many of us have cherished memories of catching them and keeping them in mason jars or running through fields that sparkled as if strewn with stars. But there are signs that our kids and grandkids will not grow up with the same wonderful firefly memories we had. That’s because fireflies are disappearing from marshes, fields and forests all over the world. And if it continues, fireflies will fade forever.

“Why are fireflies disappearing?” It is a good question and the truth is that nobody really knows for sure. Oh, there are many speculations, and in most cases the problem comes down to we humans.

“There’s no doubt the severe drought we had a few years back affected them, too,” adds Drees, who is a Texas AgriLife Extension Service entomologist. “The lack of water has to be one big reason why you don’t see as many as you would in years gone by, but there are probably other reasons, too.”

You bet there are; urban sprawl, light pollution and the over use of pesticides are at the top of my list!

“Most insects need a certain level of moisture in their environment, so drought can play a big role in their numbers,” adds Riley, a curator for the entomology department with a joint appointment with Texas AgriLife Research. “But another likely reason is urbanization – most insects need natural settings in which to live such as woods, meadows and creeks. In places where you have a lot of homes and concrete, you will find fewer insects, and lightning bugs are certainly affected.”

Both experts agree that there has been very little research over the past decade to determine why there appears to be fewer fireflies, which are technically beetles and not actually flies at all.

“As to whether pesticides are to blame,” says Drees, “it is very probable, but there is no definite research. There are just not that many scientific studies to look at that come to any single or group of definitive answers.”

Any way you look at it, fireflies are interesting bugs. They produce a chemical reaction inside their bodies that allows them to light up. This type of light production is called bioluminescence. Firefly lights are the most efficient lights in the world; 100% of the energy is emitted as light. Compare that to an incandescent bulb, which emits 10% of its energy as light and 90% as heat. Because firefly light produces no heat, scientists refer to it as “cold light.”

The environment of choice for this marvelous beetle is warm, humid, near standing water of some kind and in tall grass. They’re nocturnal, and during the day they spend most of their time on the ground. At night, they crawl to the tops of blades of grass and fly into tree branches to signal for mates. Long grass conceals the fireflies better and allows them a better vantage point for signaling at night, and over-mowing your lawn will disturb your firefly population.

The problem is that throughout the world, our open fields and forests are being paved over, and our waterways are seeing more development and noisy boat traffic. As their habitat disappears, firefly numbers dwindle. Pollution, and increased use of pesticides also contribute to destroying firefly habitat and their natural food sources.

Human traffic is believed to disrupt firefly habitat as well. While scientific studies have only been done for the past few years, there’s plenty of anecdotal evidence in areas that were once full of fireflies, and much of it goes back generations. Some areas once had so many fireflies that they profited from running firefly tours in marshes and forests, but since human traffic has increased, firefly populations have gone down.

Most firefly species have one thing in common: standing water, but they don’t need a lot of water to get by. Temporary pools and small depressions that hold water just during the firefly mating season can provide the habitat fireflies require.

Scientists aren’t completely sure what most species of fireflies eat.It’s probable that firefly larvae feed on different prey from that of adult fireflies, this is not uncommon with insects. The larvae are believed to be carnivorous, living off smaller insects, snails and slugs. Adult fireflies may also live on other insects, as well as pollen and plants, but it’s possible that some species don’t eat anything, after all, their lifespan is only two weeks long. But scientists believe fireflies thrive in wet areas because their prey does as well.

Fireflies love humid, warm environments.In the US, almost no species of light producing fireflies are found west of the Rocky Mountains. The western US does have fireflies, but just not the flashing kind. They have some glowworms, where the female will give off a constant glow while on the ground, but most of these females can’t fly. No one knows why the flashing fireflies never made it past the Rockies, although there are warm and humid areas to the west.

What can you do to bring the fireflies back? Why not create a firefly refuge in your own backyard? Ecological damages are not easily reversed because they cannot be undone, and only remedied to some extent. But that shouldn’t discourage us from trying. A few of the measures we can take to welcome the fireflies back are:

Preserve wild hubs – A bit of wilderness left undisturbed in the farthest corners of the garden will welcome these insects.

Increase tree cover– The female fireflies park themselves on the cracks of tree barks awaiting their dates. They need some privacy.

Avoid chemical use– Turn to natural pesticides and composting to make your gardens healthier for you as well as the fireflies.

Reduce mowing frequency–The taller grass will provide the much-needed cover for the adults as well as the larvae.

Install water features in the garden– They encourage the growth of slugs and worms that the larvae feed on.

Reduce exterior lighting–Let them have a better chance at increasing their numbers. Businesses have to flash their signboards to attract customers, but do we really need our outdoors to be lighted up so brightly? If people are educated about how light pollution is driving fireflies away, a collective effort can be made to keep residential hubs dark enough to welcome them back, while still being lighted enough to be safe for us.

Awareness of the plight of butterflies and the sudden dieoff of bees has brought much scientific research and grass roots efforts to their problems which is helping these beneficial insects, isn’t it time we all put a little effort into the plight of the firefly? I don’t know about you, but I believe that if we sit ideally by and allow fireflies to disappear from the Earth, then our summer nights will become a little darker and a lot less magical! Shame on us if we allow this to happen. PHOTOS BY JOE URBACH

Dripping Springs Century-News

P.O. Box 732
Dripping Springs, Texas 78620

Phone: (512) 858-4163
Fax: (512) 847-9054