(timelapse photos of Photinus pyralis in flight. fly left, fly right from Wikimedia)
14 July 2026
Last night after sunset I sat on a park bench and watched fireflies (a.k.a. lightning bugs) in my city neighborhood. I could tell by their flash patterns that they were Photinus pyralis, the common eastern firefly, because the males glowed while ascending in a J shape. Females flashed from the tips of grasses to attract a mate.
You can see both behaviors in this video by Radim Schreiber at fireflyexperience.org.
The lightning bug’s flash is generated by a light-producing enzyme called luciferase. Close up the flash looks like lightning in a cloud.
The combination of color, flash and pause pattern, and flight path are unique to each species(*). Notice how different the flashes are for this species, the cypress firefly.
Watching fireflies is such a peaceful activity. Enjoy the summer night with fireflies.
(*) The pattern and length of pauses and flashes is unique to each species except … Females in the predatory firefly genus Photuris can mimic the lights of smaller species in order to attract and eat a male. Pennsylvania’s State Insect, Photuris pensylvanica, is in this predatory genus. It was chosen because it has Pennsylvania in its scientific name.
Thanks, Kate for this information and videos. I’ve always been a fan of lightning bugs and always try to catch one as a reminder of summer as a child when we would catch them in a jar to observe them. We would eventually release them.
My question is where do they go during daylight hours?
Good question, Michael. I found out they hide from predators in shady, cool (good luck today!) and humid places on the ground, in tall grasses, under shrubs or hidden in fallen leaves. It turns out that the place I was watching them has garden plots with tall grasses. Aha!