Fireflies

From above and below-see the glow?

From above and below-see the glow?

“Hey, Mrs. Tucker, come quick! We found something!”

I enjoy such interruptions at my back door, and I run over to my young neighbors. They know I like “discovering” things. I tell them, “You’ll never see anything unless you LOOK”, so they’re pleased to have something to show. They herd me to a tree bathed in warm sun. Before we even get there, I know what we’ll find. Sure enough, it’s fireflies.

Fireflies winter-over in crevices and cracks. On a nice day you can find them basking on trees where they creep from their hidey-holes behind the bark to enjoy the sunshine. Recently on a nature walk at Hill-Stead, the group found about fifty on the elm tree out on the front lawn.

The group seemed surprised when I identified them, and someone exclaimed, “They’re BEETLES.” Well, it’s true, they are. These deceptively named insects are members of the coleoptera family (beetles) and not flies (diptera) at all. With a hard, black body, a pretty red head, and a distinctive body shape, it is hard to identify them as anything else.

Fireflies aren’t just bugs that can light up your mom’s old mayonnaise jar. They are fascinating examples of the many mysteries still held by nature against the peering eye of science.

Part of the allure is their ability to produce “fire”, which is not fire at all but bioluminescence. It is “cool”, though. The bugs light up, but never get hot. Fireflies have special light-creating organs which use a combination of oxygen and a chemical called luciferin to create the glow. What isn’t known is how they regulate the light. Where the on-and-off switch is located is still a mystery. Firefly light is not steady like a lighthouse beam, it looks more like Morse code being transmitted by a tiny flashlight. Unique patterns belong to different species.

Like most adaptations, the light has more than one use. For starters, the brightness is meant to advertise the bitter taste of the firefly, to deceive would-be predators. The flashing may also attract the attention of a female firefly as she waits in the grass for a male. If he has the right combination of blinking lights she may flash back. Studies show that the longer and quicker a male flashes, the more likely he is to be selected by a female.

But there’s a catch. The longer the firefly flashes, and the more conspicuous his flashing, the more likely he is to find himself becoming someone’s dinner, instead of someone’s date! Cannibalistic fireflies and other enemies can take advantage of the display, finding and killing the hapless suitor.

It sure is hard to square the true-to-life drama of sex and death going on outside with a peaceful image of warm summer nights and cheerily blinking insects!

I tell the neighborhood kids they found fireflies, and nobody is disappointed that they are not really flies. Kids don’t have so many preconceived ideas about what nature “should” be. A “fly” that is really a beetle is ok. It has a little black shell and doesn’t bite. You can hold it. Plus, it lights up. “Cool!” they say. You bet, I tell them, in more ways than one!

I welcome your nature questions and comments! See you on the trail, Diane Tucker, Estate Naturalist

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4 Responses to “Fireflies”

  1. James Dowling-Healey Says:

    An excellent blog. Great information!

  2. Ratty Says:

    I have always loved fireflies. When I was a kid, I lived in a place where there were so many on summer nights that you could wave your hand in the air and scoop up several of them. Seeing the first firefly of the year is still one of my favorite things.

  3. Heather Says:

    The first and only time I had seen fireflies was when I was eight at my Uncle Jack’s house on Long Island. They were so foreign to me as a kid growing up in California, but so exciting. Thanks for deconstructing a bit of their mystery. I hope to see some again soon.

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