Twinkling Fireflies Are Fading From Summer Nights

Fireflies are synonymous with warm summer nights; they light up the sky and add a bit of magic to North American summers, but recent studies have shown that firefly populations are declining, and there are numerous threats to the populations.

Fireflies in Forest
Firefly populations are declining across North America.

Small lights floating through the sky on a warm early summer night, that’s what many people think of when fireflies are mentioned. They are inspiring, nostalgic and a little bit magical. These little lightning bugs almost don’t seem real. And now studies suggest that future generations may not have the opportunity to see the twinkling light of these bugs as populations decline due to a number of factors.

Threats To Firefly Populations

Globally, there are over 2000 species of fireflies that love temperate conditions with wet, warm summers. They often live near standing water, where there is tall grass or vegetation they can hide in during the day before coming out to thrive at night. Firefly season in the United States is from late spring to early summer.

A 2024 study published in Science of The Total Environment looked at data from over 24,000 firefly surveys from the citizen science program Firefly Watch. The researchers aimed to study ecological patterns and their impacts on North American firefly populations.

Their research showed that the firefly population was most impacted by a few things: habitat loss, light pollution, changing soil conditions, changing climate and weather patterns, and land cover characteristics.

When it comes to weather and climatic patterns, the researchers suggest a strong link to climate change. This is because areas where firefly populations live are seeing increased temperatures and increasing heat waves. Firefly populations are not able to adapt to a change in the climate of their habitat, which could mean the disappearance of certain species.

“Subtle changes in climate patterns, especially related to temperature, are significantly impacting firefly breeding cycles and habitat quality,” said Darin McNeil, in a press release, the study's principal investigator.

Increased urbanization is destroying firefly habitats as cities grow. Pesticide use harms the insects. And light pollution also has a large impact, as the bugs need dark nights to thrive, and artificial light can alter their life cycle and development phases.

Saving The Bugs That Light Up The Sky

In 2024, the U.S. Fish and Wildlife Service proposed listing the Bethany Beach Firefly as threatened under the federal Endangered Species Act. This particular firefly lives in Delaware, Maryland, and Virginia. According to the proposal, the largest threat to the firefly species is climate change, as rising sea levels and increased storms threaten their habitat.

To conserve North American firefly populations, a few things must happen, according to the researchers. First, populations need to be continuously and consistently monitored. Second, the impacts of climate change need to be mitigated to decrease habitat changes and temperatures. Lastly, insect-friendly conservation practices need to be implemented. When it comes to the last two, these are important for all insect populations across North America.

Fireflies are not likely to disappear completely, but there is a danger of seeing fewer species and biodiversity as habitats change.

News References

Service proposes protections for the Bethany Beach firefly. U.S. Fish and Wildlife Service.

Illuminating patterns of firefly abundance using citizen science data and machine learning models. Science of The Total Environment, 2024, McNeil et al.