7 Things You Didn't Know About Fireflies

A summertime favorite, fireflies are famous for their on-again, off-again flashing patterns, but there's a lot more to them than that. Read more to delve into the world of our firefly friends, a world that includes toxins, an insect chemical arms race, and outright deception. For more, check out The Firefly Book at www.brettortler.com .

1. Fireflies Are Toxic!

Via Flickr User: s58y; Creative Commons Attribution 2.0 Generic License

It's true! Fireflies light up in part because they are toxic, and they want other critters to know about it. They contain toxins similar to those found in some toad species; while they aren't dangerous for humans, don't feed them to your pet. A few pet lizards that were fed fireflies died soon after consuming them.

2. Each Firefly Species Has Its Own Flashing Pattern

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Just as birds have specific songs and calls, each firefly species has a specific flashing pattern. In fact, identifying a flashing pattern is the easiest way to identify a species. That pattern is similar to a bird song and helps males locate a mate.

Males usually fly through the air signaling (so all the flying fireflies you see are male), and females signal back from the ground or vegetation.

3. One Group of Firefly Species Mimics the "Call" of Another Firefly Group, In Order to Lure Males to Their Deaths

While we think of fireflies as beautiful little creatures, nature is a cutthroat place. In fact, one group of firefly species (the genus Photuris, to be precise) are known as the 'Femme Fatales' because females mimic the call of the Photinus genus. They do so because the Photinus male will then fly toward the Photuris female, intent on mating. But instead of getting a date, he gets eaten. (The Photuris female does this in order to absorb the firefly's toxins, which Photuris fireflies lack.)

4. Fireflies Light Up Because They Are Nature's Chemistry Labs

Flickr: cjp24 / Via Flickr User: Jean-Pierre, via Creative Commons 2.0 Attribution Sharealike License

Fireflies are beloved because they light up, but it's amazing they can do it at all. When a natural organism can produce light, it's called bioluminescence. While it's somewhat common in the ocean, it's rare among insects.

How do they do it? Chemistry. While the process isn't perfectly understood yet, fireflies produce a compound called luciferin, which, when mixed with a few other compounds, produces the characteristic flash of a firefly.

5. Some Firefly Species Don't Just Blink Once or Twice: In Some Species, the Males Light Up All At Once

In most firefly species, a male blinks, and then a female responds. In some species, however, all of the males light up all at once. The result is one heck of a show. If you want to see it, head to the Great Smoky Mountains National Park in June. But before you head out, know that you'll have company. The event draws tens of thousands, and to attend you need reservations.

6. Fireflies Have Led to Brighter LED Bulbs and Even Aided in Medical Research

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Research into firefly luminescence has led to in a wide variety of fields, including LED design, biology, and even medicine. As it turns out, the genes that are responsible for producing luciferase (the compound that makes fireflies glow) can be spliced and inserted into a target organism. When the genes are passed on, they light up. This has found many uses in biology and medicine, and is a novel way to visualize certain varieties of cancer. One study of such "firefly-enhanced" mice literally caused cancer-ridden mice to glow.

7. Fireflies Are Disappearing

Flickr: makelessnoise / Via Flickr User makelessnoise; Creative Commons 2.0 License

If you've noticed that fireflies seem to be rarer than used to be, you're not alone. In many areas, fireflies appear to be disappearing. Where there were once dozens or hundreds of fireflies, there are now a few, or maybe none at all. What's to blame for their disappearance? Three factors likely play a role: (1) light pollution, (2) widespread use of broad-spectrum insecticides and (3) habitat fragmentation.

As light plays a key role in the firefly's mating process, it makes sense that light pollution affects fireflies negatively. Sadly, light pollution is everywhere. In urban areas, only a handful of stars are visible and one can practically read by the reflected light. (In a truly dark sky, thousands of stars are visible.)

The other two factors are somewhat related. In urban and surburban areas, land is increasingly portioned off for houses and developments. This splits up the firefly's habitat. Worse yet, in an attempt to kill off undesirable insects like mosquitoes, homeowners often apply broad-spectrum insecticides. The trouble is, they don't just kill mosquitoes; they kill a whole host of (often beneficial insects), including fireflies.

Thankfully, firefly aficionados are taking notice and trying to protect fireflies. One example is the Firefly Watch project, based out of The Museum of Science in Boston, which tracks fireflies by year.