News that a firefly not seen for many decades has been rediscovered is exciting wildlife enthusiasts.  

The similar firefly was spotted during a survey of a meadow in Delaware , United States. Before this, it had not been documented since 1983. 

The rediscovery was included in a recent paper published in the Journal of Lost Species. This is the largest global search for species without documented sightings for 10 years or more. 

The firefly historically ranged across parts of the eastern and southern United States. Little is known about the species, but it is known to prefer fields and meadows located close to water. 

Entomologist and ecologist Christopher Heckscher, who made the discovery, said: “I was confident I had found the species the moment I saw the flash pattern. The amber color of the flash and the long rhythmic pattern did not match any other firefly I was familiar with in this region.

“There’s hardly any information out there about it,” said Heckscher. “That’s true for a lot of our fireflies, even our common species. It blows your mind because you think of them as a charismatic insect, and you think every kid, if they wanted to be an entomologist, would be running around catching fireflies.”

Before the firefly was lost to science in 1983, scientists had not studied the species in depth.

Field studies

Heckscher surveyed three different sites in a bid to find the similar firefly between May and June 2026 in the mid-Atlantic states of Delaware and Maryland, visiting Fair Hill Natural Resources Management in Maryland and White Clay Creek State Park in Delaware, but found no similar fireflies at those sites.  On the last night of his surveys on June 3, he visited Brandywine Creek State Park in Delaware, where he focused on searching a mature meadow with shrubs, brush and plenty of low vegetation. 

Delaware’s Department of Natural Resources and Environmental Control (DNREC) carefully manages 34 nature preserves to protect their natural and cultural features. The park includes four nature preserves, and its hilly topography is distinct within Delaware, which is primarily flat.   

“The habitat is not terribly common,” said Heckscher. “We think of fields and open meadows as being pretty common, but most times we’re managing them for other things, maybe livestock, or we’re mowing them once in a while. The fact that this was just allowed to grow naturally as a meadow- that’s probably what this firefly is keyed in on in terms of its habitat.”

Identification

During his field studies and as night fell, Heckscher watched as fireflies emerged and began to flash their bioluminescent signals in the park’s meadow. He began to record the flash patterns. Male similar fireflies flash a unique string of short, amber-colored pulses of light to attract females. Males typically emit between 10 and 20 pulses in quick succession, followed by a short break. The pulses are then resumed. 

Heckscher was able to see between eight and about a dozen fireflies flashing the pattern that matched the similar firefly. He also saw spring four-flashers (Photuris quadrifulgans), a species that also has a flicker-flash. These were located in the meadow, and he believes it may be possible that other lost fireflies that prefer that type of meadow habitat could be living there as well.  He observed one of the fireflies under a microscope and was able to see genitalia characteristics only known to belong to the similar firefly. 

“The discovery of this long-lost firefly is a testament not only to the division’s mission of protecting and preserving open space and critical habitat in Delaware, but also to the long history of state parks supporting and encouraging scientific research,” said Chris Bennett, environmental stewardship program manager at the DNREC Division of Parks and Recreation in Delaware.

Follow-Up Surveys

Scientists will need to conduct follow-up surveys in similar types of habitats in Delaware and other areas to understand the current range of the similar firefly, and its population size.

“Many people are unaware that the U.S. has so many different firefly species, let alone that many of these have been lost to science for a decade or more,” said Candace Fallon, senior conservation biologist and firefly lead at the Xerces Society, which coordinates the Firefly Atlas, and one of the authors of the paper published in The Journal of Lost Species.

“The good news is that a lot of these species likely aren't gone forever—they are simply overlooked. And we've found that increased awareness, targeted searches by experts, dedicated funding, and data sharing by community scientists can lead to some pretty incredible rediscoveries.”

The recent paper on the status of fireflies in the U.S. and Canada highlighted that there are 69 firefly species with knowledge gaps about their conservation status and 48 species with no data at all.