Gossamer Tapestry

Reflections on conservation, butterflies, and ecology in the nation's heartland

Wednesday, July 16, 2008

Fireflies and Femmes Fatales

I'm sitting in my screened porch typing this blog entry. It's dusk and the fireflies are twinkling on my lawn. It has been an excellent year for fireflies here in Illinois. Right in my front yard, there have been dozens flashing every night for weeks now.

A lot of the luminescent acrobatics are about sex. The males fly about and flash in a complex pattern of blinks. The females sit in the grass or on bushes. When one sees flashes in her species' pattern, she waits a precise amount of time and answers with a single flash. The male then descends to mate with her. Usually.

In some cases, female fireflies give the response signal for other species. When a male arrives, instead of getting a little action he becomes a meal. These dangerously deceptive females are known as femme fatale fireflies.

"Don't give me any of that 'hey, Baby' crap. Urrp."

For a long time, I thought that firefly luminescence was all about sex- or occasionally deception. This spring, while preparing my firefly talk, I discovered a new wrinkle. Fireflies are toxic. They contain compounds similar to bufotoxins- the poisons in toad skin. The luminescence may also be a warning or aposematic signal. "Don't eat me- you'll barf. " Some investigators believe that femme fatale fireflies perform their dastardly deeds (sorry, anthropomorphizing) consume males of other species to gain there toxins rather than simply to gain an energy source.



At 05:12, Blogger Lemuel said...

Since fireflies (lightning bugs as were commonly call them) are common here, I was delighted to read this post. In short fashion I learned a lot about these creatures that have given me so much summer pleasure in my lifetime - from catching them to just sitting and watching their summertime light show.

At 05:50, Blogger cedrorum said...

One of my fondest memories from my childhood was trying to catch fireflies on my great grandparent's property in West Virginia. I was so pleased to see them again when we moved to South Carolina in 1999. Actually, I was very close to doing a post on fireflies yesterday. I'm glad I didn't now as yours is much better than anything I was going to write.

At 07:37, Blogger Floridacracker said...

Not many here this year and they are noticed for their absence. At times there are hundreds at once here.
Nice pictures!

At 12:15, Blogger Texas Travelers said...

I have to get down to the Trinity River bottoms and photo some fireflies. Thanks for sharing the information and post.


PS: Black and white Zebra was photographed at the Ft. Worth Botanical Gardens. There are lots of yellow on black/brown forms there.

At 12:49, Anonymous Mark H said...

I didn't know this about fireflies!! It's tough living in a Bug World... I have always found the mating of some spider's to be dangerous, but was unaware that appears to be fairly common in many insect species, eh?

Whew! That's the world Bush belongs in maybe.... THANKS, Doug.

At 14:33, Anonymous Anonymous said...

She bit his head off! Are you sure they weren't husband and wife? Anyways, he sure lost the argument.

All kidding aside, this was an awesome post. I have waited all my insect-loving life to see this phenomenon for myself. I'm a little jealous.

At 18:14, Blogger T.R. said...

Wait a minute. You mean in any given dusky, damp swath of woods there are more than one firefly species? And if you alight on the right one you get sex and if you don't you become dinner? Dinner or a little toxin vampirizing. I want your job!

At 07:19, Blogger Doug Taron said...

Lem- I agree, fireflies are one of the real joys of summer.

cedrorum- If L and I ever do move to the Pacific Northwest, fireflies are one of the things that I will really miss.

FC- Interesting given that we're having such a good year for them up here. I'll bet your drought has something to do with it.

Troy- I enjoy not having to go anywhere to see fireflies. Ft. Worth seems very far north for zebra longwings. Were they outside, or part of a butterfly exhibit?

Mark- It's one of the many reasons that I'm glad not to be a bug.

TR23- Heheh, I've wanted to see this for a long time, tooI just got lucky. As you can see from the background of that picture, they're on a sheet. This all happened while I was blacklighting.

tr- Fireflies are difficult to key out. There are three main genera in the US. Telling which species within a genus you have can be quite a chore. The flash patterns have been used to distinguish species. And there are all kinds of unexpected variations- for example, day flying species that are not luminescent as adults. However, their eggs and larvae do glow.

At 16:39, Blogger Kathiesbirds said...

Doug, I can't believe your wrote about firefiles as I just saw some while in the east, though not as many as I remember from my childhood. I'm glad they are thriving where you are. They are a happy summer memory for me. It's interesting that you should mention the toxic toads for I had my first experience with them last night and just posted about them today!

At 00:43, Blogger Ur-spo said...

i have patients who do the same things.

At 09:41, Blogger Texas Travelers said...

The Zebras were outside and breed there.

I suspect they were released from a wedding ceremony years ago when that was a popular thing to do.

They have permanent residence there now.



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