“Burn the land and boil the sea. You can’t take the sky from me”
Oh…wait. Sorry I started the wrong blog. Let me start again...
Fireflies:
For the last several nights fireflies have been lighting up my backyard. It’s a small yard and the count of fireflies is easily above 30, closer to 40, perhaps more. They are hard to count, in the dark, when they become active. These nocturnal beetles, they are beetles, fly around my yard flashing, in order to attract that special someone.
Back to the bugs, bugs? actually true bugs are just one of the Order of insects. Insects, of course, are 6 legged, jointed appendaged, exoskeleton covered, segmented, animals. The Order Hemiptera contains the true bugs. Fireflies belong in the Order Coleoptera with all the other beetles. In beetles the first pair of wings is thicker and hardened. This hardened pair protects the second pair underneath (this second pair are used to do the actual flying). Other Orders of insects (there are 24) include the Lepidoptera (butterflies and moths), Orthoptera (crickets and grasshoppers), and Hymenoptera (Bees and Wasps).
But fireflies, or in some parts of the USA they are called lightning bugs, are the ones they give delight on summer nights.
As just mentioned there is not just a single firefly species. The family of fireflies is the Lampyridae and it contains thousand of species. In my backyard the genus of firefly is Photinus. I do not know what species I’m seeing on these nights, perhaps more than one. Or maybe earlier in the evening one species comes out and as the night turns to full darkness, another species emerges. As far as beetles, the Order that contains the Lampyridae family, as J.B.S. Haldane is thought to have said, “God has an inordinate fondness for beetles”—or some variant of that: There are over 300,005 species of beetle.
What evolutionary events led to light being used to attract a mate.
Other animals have behaviors, sounds, sights, and smells, that are used for that purpose. Why light, well… why not light….. Perhaps it started as a “look how cute my butt is” since they mate butt to butt ( perhaps not exactly what you are imagining right now but work with me here). Then to show their prowess (or health), a male butt was the focus of selection pressure. Shiny butts attracted more mates. This led to a race of shiny butts, which in turn led to some spark of light eminence. The first male to have a light producing butt, a photic organ, was swooned with mates and…well the rest is history.
Let’s back up for a second, remember insects have three parts, head, thorax, and abdomen. Fireflies have reproductive organs at the tail-end of their abdomen. The male part is called the aedeagus, which connects to the ovipore of the female. These are the parts they are touching together in my photo above. I do not know which one is male and which female. Again NSFW, shield your eyes.
I wonder about deep sea fishes at light emitting organs. In deep sea fishes, and other deep sea organisms, bioluminescence of some kind is more common than in your local lake. Is mate attraction a common use of that adaptation? Light, in deep sea fishes, it turns out, is used for mate attraction, and all sorts of other things. These uses include, scaring predators away, attracting prey, counter shading against light from above, and perhaps many more things, since studying deep sea fishes is tough. Maybe studying fireflies will give us more clues. But, let me but in, fish don’t really have butts either…do they?
- Do individual fireflies come out every night, that is , are the ones I’m seeing in my backyard the same ones, or mostly the same, every night?
- How many matings can an individual do in a night? They seem to be able to mate and then go back to attracting more mates; evidenced from one of the pairs I saw mating, who, when done, one of them flew into the air and immediately started blinking again. I think this one is the male.
- Most people do not like beetles, but fireflies are beetles. Is this more evidence that people are drawn just to the superficial?
In light of research that shows that the number of insects has been dropping, it is great to see the fireflies going at it in my backyard. Don’t worry to keep the kids safe I’ve put up an adults only sign.
Notes:
FYI, I don’t think appendaged is a real word.
Sources and further readings:
Gould SJ. 1995. Dinosaur in a Haystack: Reflections in Natural History. Harmony.
Hallmann CA, Sorg M, Jongejans E, Siepel H, Hofland N, Schwan H. et al. 2017. More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PLoS ONE, 12, e0185809.