Summer nights are full of little lights. Look up on a clear night and see a sky full of stars and the constellations humans have created from them. The Big Dipper and Cassiopeia never leave us, but by August, we have sent Orion well on his way and can look up to see the Summer Triangle of Lyra, Cygnus, and Aquila, among many others.
Come back down to Earth on that same warm summer night and you can see a ground level twinkling light show. Whether you know them as fireflies, lightning bugs or the more scientific family name, Lampyridae, they are a familiar summer sight in open areas such as fields or backyards.
As a child, I knew that they were using those lights to talk to each other, but I was much older when I learned more about what they were trying to say. Adult fireflies use blinking light patterns as a courtship and mating ritual. There are some exceptions to this rule and therefore some fireflies do not produce light at all, but with almost 2000 species, some variation is inevitable.
These fireflies that we see on a summer night are bioluminescent. Bioluminescence is not exclusive to fireflies. It exists in other organisms as well, largely marine species and fungus. Some organisms have bacteria in their body creating this light, while others, like our fireflies create and emit light using a specialized organ under their abdomen. They take in oxygen and combine it with a compound called luciferin to produce the light we see.
Each species lays claim to their own unique pattern of flashes in varying shades of yellow, orange, or green. The males are generally the ones flying around in the air. They use these timed patterns of flashing light to send a signal to the females of their species, who are down on the ground or sitting in bushes. The females can then choose to respond in turn with their own precisely timed pattern if they are interested. There are usually far more males in any given area than females so they can afford to be choosy. The next time you see fireflies, take a closer look at their location. How many do you see on the ground? How many females in comparison to those more frequently blinking males make lazy loops in the air?
Although a firefly’s adult stage is more easily accessible thanks to the time they spend flying around our yards and fields, the larval stage has the capability to glow as well. Since they are not mating during this stage in their life cycle, that glow acts as a warning to predators that they taste terribly bitter and should not be eaten.
Fireflies are insects, specifically a type of beetle. Like many insects, they begin life as an egg and hatch out into their larval form. Although they are nocturnal, you can find them during the day by exploring under logs or in the leaf litter. They are usually black, sometimes with red down the side of their body, and their structure reminds me of overlapping plates of armor when looking at them from above. As larvae, they eat slugs, worms and other insects. After one or more winters hibernating, they will eventually go through metamorphosis. The larvae then enter the pupal stage where they will completely transform their bodies into their adult form. They will only spend a couple weeks as adults and this time is largely spend searching for a mate, mating, and laying eggs.
Some of us are lucky enough to see this lightshow from our front porch. For others, a drive out of town to an open field is required. Unfortunately, fireflies are not successful in mating when faced with large amounts of light pollution. Either way, most spectators who watch varying firefly species appear as the sun sets and switch out throughout the night simply view their appearance as a pretty sight. What most of us forget is that you are actually watching a nightly drama of intense competition as these males strive to be best in show in their effort to pass on their genetic line.
Audubon Community Nature Center builds and nurtures connections between people and nature. ACNC is located just east of Route 62 between Warren and Jamestown. The trails are still open from dawn to dusk as is Liberty, the Bald Eagle. Though the Nature Center is currently closed, including restrooms, due to COVID-19 restrictions, drive-thru sales are available from the Blue Heron Gift Shop and Day Camps are open. More information can be found online at auduboncnc.org or by calling (716) 569-2345.
Chelsea Jandreau is a Nature Educator at ACNC.