Preecha Jiabyu used to take tourists on a rowboat to see the banks of the Mae Klong River aglow with thousands of fireflies.
These days, all he sees are the fluorescent lights of hotels, restaurants and highway overpasses. He says he'd have to row a good two miles to see trees lit up with the magical creatures of his younger days.
“The firefly populations have dropped 70 percent, in the past three years,” said Preecha, 58, a former teacher who started providing dozens of row boats to compete with polluting motor boats. “It's sad. They were a symbol of our city.”
The fate of the insects drew more than 100 entomologists and biologists to Thailand's northern city of Chiang Mai last week for an international symposium on the “Diversity and Conservation of Fireflies.”
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They then traveled Friday to Ban Lomtuan, an hour outside of Bangkok, to see the synchronous firefly Pteroptyx malaccae – known for its rapid, pulsating flashing that look like Christmas lights.
From backyards in Tennessee to riverbanks in Southeast Asia, researchers said they have seen fireflies dwindling in number.
No single factor is blamed, but researchers in the United States and Europe mostly cite urban sprawl and industrial pollution that destroy insect habitat. The spread of artificial lights also could be a culprit, disrupting the intricate mating behavior that depends on a male winning over a female with its flashing backside.
“When you talk to old people about fireflies, it is always the same,” said Stefan Ineichen, a researcher who studies fireflies in Switzerland. “They saw so many when they were young, and now they are lucky now if they see one.”
There are some 2,000 species and researchers are constantly discovering new ones. Many have never been studied, leaving scientists in the dark about the potential threats and the meaning of their Morse code-like flashes that signal everything from love to danger.
A nocturnal insect as small as a human fingertip can't be tagged and tracked like bears or even butterflies, and counting is difficult when some females spend most of their time on the ground or don't flash.
Scientists acknowledge the urgency to assess fireflies may not match that of polar bears or Siberian tigers. But they insist fireflies are a “canary in a coal mine” in terms of understanding the health of an ecosystem.