PVNWG member Joy Pardue wrote the following in response to our July 2009 reading selection, Hollow, Peepers and Highlanders: An Appalachian Mountain Ecology, by George Constantz.
For weeks I’ve been enjoying a soundless light show each evening as fireflies flit about our yard signaling, twinkling, creating a wonderland and doing what fireflies do this time of year. Turns out they do much more than we’d ever suspect. When Constantz’ book arrived, I scanned the contents - “Femmes Fatales of Twilight” was the first title to catch my eye. This subject could only be those charming Tinkerbelle’s that close the day on a magical note so I eagerly turned to Chapter 11 and began to read.
This essay started off w/ Robert Frost’s charming poem entitled “Fireflies in the Garden” and I really liked the phrase “And here on earth come emulating flies”. Learned these enchanting insects emulate more than heavenly bodies. By the end of the second paragraph I learn their society is rife w/ “liars and cannibals” which is a serious accusation. Such a strong statement prompted me read on. By the end of the chapter I was thoroughly impressed at the level of sophistication these tiny creatures achieve. For an organism that probably doesn’t have enough neurons to qualify as a brain, they are as conniving as criminals.
Here I learned about aggressive mimicry – a form of predation which, as one would expect, gives an organism a survival advantage. In this particular case, it’s about eating well. After successful breeding, Photurus females mimic Photinus males to lure them close enough to consume them. Literally. Once the female is gravid, she has neither need nor interest in mating. Devouring a robust male “increases the number, and possibly the quality, of the eggs she produces”. For a Mama whose inexorable goal is to have her babies survive and thrive, this is a ‘no brainer’ which is convenient for an organism which basically doesn’t have one.
As in all warfare, the other side must continuously up the ante so it’s no surprise that this is precisely what happens next. At some level, males “sense” the danger. Their dilemma offers them two extremes: the highly desirable possibility of mating or the fatal one of being
cannibalized. No wonder he approaches cautiously. He’d be even more guarded could he comprehend that 16% of males of his species provide the fuel that generates offspring for another species.
As Constantz eventually points out, “it gets even more bizarre”. These wee beings then come up with the complex scheme of “mimicry of a mimicry”. After a convoluted discussion, the author attempts to explain this “step-by-step evolutionary arms race” but the details escape me as I’ve lost track of who is deceiving and/or devouring whom.
Constantz then wraps up this saga w/ a “pleasing finish”, telling us of Asian fireflies that “flash in rhythmic synchrony” producing a light beam almost as penetrating as the beacon of a lighthouse. And we learn that Photinus carolinus perform a similar show in The Smokies. Hmmm, I’d really like to see this group perform. By then I could have been grappling w/ a calculus problem; perhaps “if I'd charted the details or made an elaborate diagram of this information, complete w/ illustrations (in color), I’d ‘get it’.”
Un-naturalist-like, I’d spent hours observing ‘my’ fireflies and the extent of my curiosity was shallow indeed. First, I was surprised to find them ‘flying high’ – reaching the tops of tulip poplars and such. As a kid chasing these creatures around the yard, I never considered their vertical range. Plus I did wonder just how females sized up males. To me, their little lanterns looked pretty much the same but perhaps the females could spot a special glow. Or vice
This is an odd twist of the notion that “the devil is in the details” but I won’t let this become a case of knowing too much. Fortunately I’m not facing the same quandary as that of the Photinus males. For now, safe on the balcony, I’m content to gaze into the darkness and savor those glimmering lights which continue to enhance the pleasure of my evening tea.