Nature’s Fireworks

Let’s play a simple game and learn how much we know – or think we know – about those adorable lightning bugs – or should I say fireflies?

True or False:

Fireflies are the same thing as lightning bugs.

All fireflies fly around at night.

Fireflies are always harmless little creatures.

Fireflies are plentiful.

Okay, so the first question is a trick question, so whatever you said, you’re right. Score one for you!

But – there is a difference between lightning bugs and fireflies. All lightning bugs are fireflies, but not all fireflies are lightning bugs. Lightning bugs generally fly at night, and they flash, which not all fireflies do.

No, all fireflies don’t fly around at night.

Fireflies are pretty harmless – as adults. As larvae, they are ferocious predators, consuming slugs and snails and worms. Who knew? But yes, firefly larvae lurk near the soil surface, resembling minute armadillos with gigantic teeth, waiting for an unwary slug or snail to slither near. They pounce (sort of), grab it with their mandibles (a cross between arms and teeth) and inject nasty neurotoxins into their prey, paralyzing it; then, they inject digestive juices to liquify the prey so they can just suck it up! So, if you hate slugs…Hurrah!

Fireflies are really winged beetles, not flies.

Fireflies aren’t nearly as plentiful as they used to be, and many species are endangered; it’s thought that some are extinct. Aw, nuts. A win for slugs.

If you’ve wondered if you’re dreaming it that there used to be many, many more lightning bugs when you were a kid, you’re not dreaming. There were. Lightning bugs have suffered from pesticides, “light pollution,” and habitat destruction to the point that some species, including the Bethany Beach Firefly, are endangered. Pesticides are a huge culprit, but the prevalence of outdoor lights can be confusing for males seeking a female. Endless lawns limit the hiding/resting places for these creatures, too.

Fireflies are in the order of winged beetles Coleoptera, more specifically, they are part of the family of Lampyridae, which is part of Coleoptera (an order is larger than a family; there’s a hierarchy, just like the army, with enlisted men, officers, etc.). So, they’re not flies, not a single one of them, but who cares? These are great words for crowd guessing games!

There are at least 170 different species of fireflies in North America alone.

We are most familiar with the flying beetles that flash and make evenings and nights interesting and fun. However, if we look carefully, we may notice that sometimes there aren’t any flashes, just a glow from a tree trunk or shrub. And sometimes, we may notice our little buddies flying around during the day.

I used to think the fireflies I saw during the day were just looking for a nice place to nap so they’d be all ready come evening, when it was time to fly about and find a mate. It’s possible some of them are doing just that – but it’s more likely that the day flying fireflies are just looking for a mate. Day fliers don’t do the “bioluminescence” (living things that light up) as adults at all. The larvae do glow, in fact, all firefly larvae glow, but not all adults do. The day flying variety skips that option, saving all their energy for reproduction. 

Many firefly species have sharply differentiated gender roles. The males fly, the females don’t. Some females literally have no wings so they can’t fly (some have very short wings that wont let them fly), but they hang around where males can see them glowing like crazy. These little cuties are often called “glow worms.” Some females can fly, but generally don’t, preferring to signal madly while remaining still and wait for a handsome male to find them. If you’ve noticed a glow coming from a shrub or tree trunk, this might be what you’re seeing.

Some fireflies reduce their progeny’s competition by eating the prospective parents of their competitors. Having mated, the females remain on a tree trunk, still glowing happily. Males of other species just can’t resist checking her out. If she’s quick, she’ll have a big firefly dinner; the chemicals in the male she ate will help her produce healthy eggs. This is one of the exceptions to a pretty good rule that adult fireflies eat flower nectar and other planty things, just getting energy to fly. Some don’t eat at all, male or female.

Once a mate is found, the females lay eggs. On the ground, in the ground, on a trusty tree trunk, wherever they think their little ones will do well. Having done so, the grown-ups are generally done for. The eggs will hatch into hungry larvae that will chase down slugs and other garden miscreants for up to two years. Like many insects, most of a firefly’s life is spent in the soil; adults – those that we see on summer nights – seldom live more than two months.

Fireflies, like many butterflies and moths, truly love it if you leave your leaves on the ground in the fall without making a huge, heavy pile their progeny will be smothered by.

The best of all possible worlds for a firefly is that you have a damp area, perhaps one that is sometimes – rarely – inundated but mostly not, just damp, where you leave the leaves. Heavy mulch will kill the little slug-killing larvae. Complete and permanent total inundation, like a pond, will also kill the little snail-killers. As with the three bears… “just right” (moist) is perfect. A reasonable layer of leaves lying on the ground in summer, particularly if they’re moist leaves lying there, is a clear signal to firefly females that this is a good place for her offspring.

It’s an almost staggering thought, but there are at least 170 different species of fireflies in North America alone. Worldwide there are at least 2,000 species, and more are added to the list as scientists discover them. With all that variety, it’s almost hard to believe they could be endangered, but, sadly, that is so. Fortunately, it’s easy to help these iconic little creatures of the night.

Want more fireflies/lightning bugs?

USE NO PESTICIDES in your yard. Inevitably they end up in the soil – wherever they’ve been applied – and they will poison the firefly larvae.

Make daytime hiding places. Fireflies – and lightning bugs, which are fireflies – love tall grasses and plants that give them shade and cover during the day. The more cover, likely, the more fireflies you will see.

Allow some leaves to remain in place throughout the year in a section of your garden. Piling them high blocks air to the soil where the firefly larvae live, but a light covering keeps the soil moist, which fireflies love.

Maureen Rice is a naturalist/gardener living in Talbot County. She is the author of “Not! Your Granny’s Garden.” Email to receive the blog straight to your inbox.

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