Scientists who have been studying the fascinating nighttime synchronized firefly displays believe they have figured out the purpose for the behavior. The insect light displays are made by males so females can decide which ones they want to respond to with their own flashes. The scientists’ experiment involved placing female Photinus carolinus fireflies in petri dishes and then using technology for producing sequences of flashing lights. The females responded to the flashing lights much more often when they were synchronized. The determination from conducting the experiment was, “We conclude that one function of flash synchrony is to facilitate a female’s ability to recognize her conspecific male’s flashing by eliminating potential visual clutter from other flashing males.”
If you consider what is being said here, it is quite fascinating. Female Photinus carolinus fireflies it appears, have the ability to see a whole light display performance made of many different male flashes, and choose from among them. The light performance is similar to a symphony, in which there are many performers who play one piece of music, and yet each player’s contribution can be witnessed and responded to by audience members.
One of the researchers, Jonathan Copeland of Georgia Southern University, was aware of synchronized fireflies in Indonesia and Malaysia, but had not ever heard of them being in the U.S., until about 1993. Knoxville, Tennessee resident Lynn Faust contacted Steven Strogatz who forwarded him her information about firefly synchronization. This quote is from her letter to Strogatz,
“These bugs ‘start up’ in mid June at around 10:00 pm nightly. They exhibit 6 seconds of total darkness then in perfect synchrony, 1000’s light up 6 rapid times in a 3 second period before all going dark for 6 more seconds… as far as we know, it is only in this small area that this particular type of group synchronized lightning bug exists. It is beautiful.”
Video of Synchronous Fireflies (Better seen in a dark room)
After visiting, he could see indeed she was correct. They wound up collaborating on a publication together, titled “The Night Lights of Elkmont” in which they described the light displays of the species Photinus carolinus: “A male produces four to eight very bright flashes in rapid succession (approximately two flashes per second). Then, he waits for eight to 12 seconds and produces four to eight flashes more. A female can be identified because her very weak pulsed flash occurs when the males are not flashing.” The Photinus carolinus species appears to be based in Elkmont, Tennessee.
Image Credit: Goldring