While light bulbs make our nights brighter, they are dimming the social lives, and survival rates, of some of nature’s natural light-makers: fireflies.
A 2021 report found that 1 in 3 North American species of fireflies may be at risk of extinction. A 2020 survey of nearly 50 of the world’s leading firefly experts identified habitat loss and artificial light as the greatest threats to the fireflies’ global populations.
This trend is not unique to fireflies. Studies show habitat destruction, climate change and pesticides are leading to declines in monarch butterfly populations across North America. A U.S. Department of Agriculture 15-year study found the number of bee species in a single forest decreased by nearly 40%.
University of Virginia environmental sciences professor Kyle Haynes has spent years researching the impact of light pollution on different plant and animal species, including fireflies, at UVA’s Blandy Experimental Farm. Haynes spoke with UVA Today and illuminated specific ways in which light is interfering with the insects’ mating behavior and shares insights on how the bugs use light to communicate.
Q. How do fireflies use light?
A. Each firefly species has a unique flashing pattern that they use to attract members of the same species for mating. They flash using different temporal sequences while dancing through the air in different patterns.
You can actually recognize individual species by their flashing patterns. There are firefly species in which the females eat the male of other firefly species. They do this by mimicking the flashing patterns of the females of a prey species to lure in and capture the males.
Of course, that use of lighting, bioluminescence, is what makes them especially vulnerable to the effects of light pollution.
