Complaints from social media users about the growing difficulty of spotting fireflies in the wild are more than nostalgia for childhood memories, scientists say. Researchers warn the disappearance of the glowing insects reflects a deeper environmental crisis that has been building for years.
Prof. drh. Upik Kesumawati Hadi, an entomologist at IPB University’s School of Veterinary Medicine and Biomedical Sciences, said fireflies are highly sensitive bioindicators whose presence reflects ecosystem health.
“Fireflies are bioindicators, meaning organisms whose presence or absence reflects the health of an ecosystem. When environmental quality declines, their populations quickly shrink or disappear,” she said in a statement published by IPB University.
The decline is not limited to Indonesia. Data from the International Union for Conservation of Nature show that about 11% to 20% of evaluated firefly species are now considered threatened, with several Southeast Asian species found in mangrove ecosystems across Indonesia, Malaysia and Thailand already listed as vulnerable.
At the national level, entomological studies point to a sharp drop in firefly populations, particularly in urban and rapidly developing areas. “These luminous insects are extremely sensitive to environmental change, from soil moisture shifts to pollution,” Upik said.
Experts identify multiple overlapping threats behind the decline. Habitat loss is considered the most significant factor, as green spaces, wetlands and rice fields are converted into residential and industrial areas, destroying the moist soil conditions firefly larvae depend on to survive.
Light pollution is another major driver. Bright artificial lighting, particularly from widespread LED use, disrupts mating behavior by making it harder for males to detect female light signals, reducing reproduction rates and gradually shrinking populations.
Other pressures include increasing use of chemical pesticides, climate change-driven drought conditions, canal concreting and ongoing urban expansion, all of which further degrade firefly habitats.
Despite the decline, fireflies can still be found in relatively undisturbed environments with low light pollution, including mangrove forests, riverbanks, wetlands, traditional rice fields, organic plantations and humid tropical forest floors.
Upik warned that without intervention, future generations may only encounter fireflies in books, museums or digital media. She urged simple steps to help preserve remaining populations, including reducing outdoor concrete surfaces, limiting excessive outdoor lighting, switching to organic fertilizers and avoiding chemical pesticides, and protecting local waterways.
“The survival of fireflies depends on the survival of their habitat. Protecting the environment also means ensuring that their natural light can still be enjoyed by future generations,” she said.
