It Must Be Summer, the Fireflies are Flashing!

How do I know that summer is really here? For me, it’s the first firefly or lightning bug. Last night, the first flashes in my backyard were met with great celebration and fanfare. I’m expecting that with our mild winter and recent rain, we should have a good firefly summer in store for us. We’ll see.

As a kid in Seattle, I never saw fireflies, so they seem all the more magic to me now.  Several members of the firefly family actually live west of the Rockies; they just don’t have light producing organs. Even though the "Pennsylvania Firefly" is the official insect of the Commonweath of Pennsylvania (Photuris pennsylvanica), at least 20 other species of firefly have been found in our state!  

Fireflies, are not actually “flies” at all. Flies only have two wings, and fireflies have four wings: two for flying and two hardened wings that fold over their back for protection. Fireflies are beetles in the family Lampyridae. I don’t think they got this name because they can turn on like a lamp, but certainly helps me remember their scientific name.

The main reason that fireflies flash is to communicate with each other. Usually a female will sit and flash in a way that attracts males of her species. The male responds with his own flashing pattern as he approaches her. If she doesn’t think his flash is up to her high standards, she can just stop flashing. He’ll never find her. How convenient! Next time you are out in the yard, see if you can see this drama playing out. Some females are a bit sneaky and flash the pattern of a different species. When he approaches, expecting a romantic encounter, she eats him. Beware! 

Identifying an exact species of firefly can be a bit tricky, but a fun thing to do is to look carefully at how the fireflies are flashing. Different species flash with different patterns and even slightly different shades of green. Some of the ones that are common here in this region give a long flash and fly in the shape of the letter “J.” Sometimes you’ll see a firefly flashing near the ground right around sunset and you'll see another well after dark, perhaps flashing in a tree. They will be different species of fireflies.

Populations of fireflies have reportedly been declining in some areas. At least part of the reason has been a loss of habitat and the widespread use of pesticides.  Light pollution might also be part of the problem. Fireflies like the grass to be long, so I don’t feel bad if I haven’t taken the time to mow recently.  “I am not lazy, I’m helping the fireflies!” If you enjoy fireflies in your garden then avoid using pesticides on the lawn. Is the desire to kill a few lawn grubs worth the cost of eliminating a free, safe and spectacular fireworks show?

One thing that will not cause populations of fireflies to decline is to let kids catch them and put them in a jar for the night. Just put a little grass in the jar, and let them go in the morning. If you are interested in finding out more about fireflies, or participating in a citizen-research program on fireflies, please visit:  https://www.mos.org/fireflywatch/