Stepped the mast of our sailboat last night and then saw this summer’s first lightening bug while walking dog. Was reminded, again, of the subtle interjection of dynamism the seasons’ change provides. Always something new to think about.
Most of the ones you see flashing are males. All of the ones flying and flashing. With their fireworks, they’re trying to impress the females in the grass below. The success rate is low because competition is high – the m/f ratio can be as high as thirty to one. The girls each flirt with up to ten different suitors simultaneously, by signaling back, before choosing one with which to bed.
How does she choose? Well, sometimes a female equates a male’s flashing sequence with the size of his package. Seriously. It goes like this: Firefly larva spend the first two years of their lives underground. They don’t eat for their two week adulthood above ground.
Along with sperm the successful male passes a protein rich ‘nuptial gift’ to his mate enabling her to produce more eggs while she slowly starves. The ecstatic coupling ordeal can last from dusk to dawn.
There are some 2,000 firefly species on the planet of which a handful will be found in North America. You might encounter several in your yard this evening. You can differentiate by the pulse pattern – sort of like Morse code. Pulse pulse, three second pause, pulse pulse = Photinus greeni. Pulse, five second pause, pulse = Photinus ignitus.
It’s thought that the ability to thus show off began in larvae eons ago as a means to convey a warning to would be predators. Bitter taste. Evolution coursed the luminance up the ontogeny to where we see it today. Still though tastes bad to most other creatures which led to another bifurcation in these insects’ family tree.
Firefly Photuris will sit in the grass feigning femininity by returning the flash of a male on wing. Said male approaches hoping to do the dirty but gets eaten instead. Photuris is thus even more repellent to potential predators.
Photuris seems to go for a rapid flash rate, just like the females. So if a bug hopes to avoid trouble and get lucky instead it should probably try to be more suave than debonair. And like Dad said, it should be careful with what it thinks.
*I read most of this stuff in the June 30, 2009 NYT
The Subtle Landscape 
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