Iowa sees more fireflies this year despite long-term decline

The pulsing, luminescent green glow of a firefly has excited kids and families for decades. This year, Iowa is seeing an increase in fireflies, but the species’ future remains uncertain.

“Iowa is a big question,” said Zach Schumm, Iowa State University insect diagnostician. “We don’t have current monitoring data (on fireflies), some are not even being monitored at all.”

There are more than 200 firefly — or lightning bug — species across North America and over 2,000 worldwide, but Schumm said the firefly population has been declining for decades due to factors such as habitat loss, pesticides and droughts.

“As we lose habitat, species, biodiversity in general is going to decline, fireflies are really not excluded from that,” Schumm said. “(Fireflies) are beneficial, they’re a huge part of food webs.”

This year, he said, people are seeing more fireflies than usual in Iowa, and entomologists are not sure why.

Fireflies come from a beetle family called Lampyridae and rely on moist environments for their food such as snails, worms and slugs. Schumm said more rain this year could be helping some species of fireflies, but more data is needed to determine the root causes.

“If you have the perfect mixture of a lot of things that they need, you can expect a better year for them,” he said. “It seems like we’re experiencing that this year, at least for some species.”

The increase is reflected in data collected by Jim Durbin, of Marion, who created the website Insects of Iowa.

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In the 1980s, Durbin started taking pictures of different animals, particularly birds, as a member of the Cedar Rapids Audubon Society.

Durbin said he began going to parks and wildlife areas across the state using a camera and a high-powered light to take photos of all types of animals, insects and wildlife species.

Each session, he would come back with 500 to 1,000 pictures. He then began identifying them and putting the number of sightings on his website.

Today, he has documented through his photos 7,103 types of Iowa insects, including fireflies, as well as more than 9,000 other species.

Durbin’s work has identified 14 firefly species in Iowa. The two most common, black and big dipper fireflies, both increased this year compared to 2024 by four to 10 sightings.

“We are trying to figure out what might be causing so many of them to be out this year versus previous years where we hardly saw any,” Durbin said.

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Brian Preston, Dubuque County Conservation executive director, said anecdotally there haven’t been as many fireflies in the county this year, but the department does not track firefly populations.

He said roughly 7,000 acres of prairie land and areas conducive to fireflies has been lost over the past 20 years due to development and environmental changes. He said this loss can harm several populations.

Preston said planting more prairie land is one of the ways to help firefly populations and other species struggling in the state.

The department tracks several species in the area, and Preston said Dubuque County Conservation is considering tracking fireflies in the future.

“I think it’s really important we monitor our populations,” he said. “We probably only think about fireflies during the Fourth of July time when we have fireworks, but we have our own natural fireworks.”

He said fireflies’ value is more than biodiversity, it’s something everyone can enjoy.

“At night it can be really remarkable,” he said. “You get into an area that still has high populations of them, it’s amazing how many thousands of them can be lighting up, just really kind of magical.”

That magic has captured many Dubuquers’ hearts over the years. Sitting with a group of friends in Eagle Point Park, Dubuque resident Gail Miller said catching fireflies was something everyone did in the summer.

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She said her fascination with them led her to bring jars full of fireflies when she visited family in Washington state as a kid.

“It was a unique thing out there because they had never seen a lightning bug.”

Walking among the flowers of the Dubuque Arboretum and Botanical Gardens, Ken and Barbara Israel were celebrating their 54th wedding anniversary Thursday.

They visit Dubuque regularly and have property in south Madison, Wis., where they still see droves of fireflies that charm family members.

“It’s packed with biodiversity and fireflies,” Ken Israel said.

Looking out over the Mississippi River with a pair of binoculars, Dubuque resident Bob Pape said conserving environment for all life is important, including fireflies.

“The outdoors are my church,” he said. “It’s important to conserve those environments that house them.”