Their light patterns are part of their mating display. Each species of firefly has a characteristic flash pattern that helps its male and female individuals recognize each other. Most species produce a greenish-yellow light; one species has a bluish light. The males fly and flash and the usually stationary females respond with a flash. Peak flashing for synchronous fireflies in the park is normally within a two-week period in late May to mid-June.
No one is sure why the fireflies flash synchronously. Competition between males may be one reason: they all want to be the first to flash. Or perhaps if the males all flash together they have a better chance of being noticed, and the females can make better comparisons.
The fireflies do not always flash in unison. They may flash in waves across hillsides, and at other times will flash randomly. Synchrony occurs in short bursts that end with abrupt periods of darkness.
Here is a pic from the Firefly Event, the pic doesn’t do it justice. This is truly an event that must be witnessed, even after a few days I still couldn’t convey the words on exactly what happened !!
The lights from the fireflies moved in waves up and down Elkmont Valley where we positioned ourselves, the pattern seemed to start far from us and be in strips of thousands of lights and would then stream across the bottom right toward us and then stop at our feet.
Then continuing on across the road at our backs towards the other side of the valley floor. There would be burst of 5 flashes quickly then it would stop for 10 seconds or so and then repeat in an almost frenzied fashion !!
The human reaction was incredible, when we first arrived hundreds of people were packed along the old roadbed that runs along the valley floor, many with lawn chairs and blankets making you think you were attending a fireworks show.
At first as the light faded you could feel the crowd growing impatient, people were laughing and talking and when one little firefly would appear they would remark is that it…I even began to wonder myself !!
The Park Rangers assured us to be patient and wait for the show, When it started the crowd was amazing, people at fireworks display usually oh and ah thru the whole event, but here there was an incredible silence as if the fear of your voice would scare them off and they would stop the beautiful display they were sharing with us.
Many in the crowd were brought to tears, including my wife, they were overwhelmed with such joy and amazement that the emotion displayed was almost as cool as the fireflies !!
Ok after this way too long post here is the pic, like I said before they are not that good and they don’t really represent what I witnessed but it is something I will have forever to help me remember that warm wonderful summer evening !!