Fireflies named insect of the year 2025 as their glow disappears from Czech summer nights
The flickering lights of fireflies used to be a familiar part of summer nights in the countryside. Yet these elusive insects are disappearing, along with many others. To raise awareness about fireflies and the challenges they face, the Czech Entomological Society named them Insect of the Year 2025. I spoke with entomologist Tomáš Dvořák from the Czech University of Life Sciences about what makes fireflies so special.
First of all, why did the Czech Entomological Society choose the firefly as the Insect of the Year for 2025?
"Every year, the Czech Entomological Society selects insects that are either endangered, important for humans, or somehow charismatic or interesting.
"This year, they chose fireflies because, even though we all know them, we actually don’t know much about how they live or what they do.
"And on top of that, we’re now finding out that their populations are starting to decline."
Is it true that there are actually three different species of fireflies living in Czechia?
"Yes, the Czech Republic is home to three firefly species.
"But only two of them are nocturnal, meaning they’re active at night. The third one is diurnal—it’s active during the day, so you won’t see it glowing at night.
"Of the two night-active species, only one glows during flight. So the glowing fireflies you usually see in summer come from just that one species."
As you said, the number of fireflies are declining. What are the biggest threats that they face?
"Globally, the main causes of firefly population decline are habitat destruction—often due to expanding cities—and light pollution.
"As urban areas grow, we destroy the natural environments that fireflies rely on. And artificial lighting at night has a huge impact. We light everything up so much that fireflies can’t see each other’s signals anymore, because we outshine them."
Why do fireflies glow? I mean, what purpose does it serve?
"In nocturnal adults, the glow mainly works as sexual communication. Males and females use light to find one another.
"In the juvenile stages, the glowing most likely serves as a warning for predators, kind of like how bright colours warn of danger in wasps or bees.
"So, depending on their stage of life, the glow can either help them reproduce or protect them."
So nowadays I would probably only see a firefly somewhere where there is not so much light pollution?
"Yeah, absolutely. You need to go somewhere darker, ideally near a forest. Look near water—like a stream or pond—or along the edge of the woods, far from streetlights and buildings.
"But by this time of year, late July, the adult season has basically ended. You might spot an occasional adult, but more likely you’ll see glowing larvae on the ground or in the soil."
So what is the best time of year to observe fireflies in nature?
"Adults are active roughly from mid-June to the end of July. That’s the best time to catch their light displays.
"Before and after that, except in the coldest winter months, you can still find glowing larvae in places where the adults had been.
"You can spot them year-round, but that one-month summer window is when the show is at its best."
The Czech University of Life Sciences has launched the public initiative ‘Czechia is Searching for Fireflies.’ What is it about and how can people take part?
"It’s connected to the problems fireflies are starting to face, including their population declines.
"We realized that here in the Czech Republic, we actually don’t know much about how fireflies are doing—where they live, how common they are, and so on.
"So we started this citizen science initiative where anyone can take part. If you see a firefly, you can record the location using GPS or just note a specific place, and we’ll add it to our database.
"This way, we’re building a map of where fireflies live, which helps us identify both the most valuable areas and the ones most at risk."
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