Male fireflies attract females with their winking backsides, but despite this innovative mating call numbers of the tiny insects are in decline, thanks to urban sprawl, industrial pollution and artificial lights.
At a conference in the Thai city of Chiang Mai, 100 entomologists and biologists discussed the plight of the firefly, which – anecdotal evidence suggests – is disappearing from habitats as diverse as gardens in Tennessee and river-banks in southeast Asia.
In Bam Lomtuan, for instance, an hour outside Bangkok, the insects were once a tourist attraction, with thousands setting the banks of the Mae Klong River aglow with natural illumination.
Preecha Jiabyu, who used to row tourists out to see them, said that nowadays only the lights of hotels, restaurants and roads were visible. To see trees lit with the creatures so abundant in his youth, he had to row two miles out of town.
“The firefly populations have dropped 70 per cent in the past three years,” Mr Preecha told the Associated Press. “It’s sad. They were a symbol of our city.”
Researchers in Europe and the US believe urban sprawl and industrial pollution have destroyed the habitat of fireflies or glow worms. The spread of artificial lights may also be a factor, disrupting mating behaviour.
“It is clear they are declining,” said Stefan Ineichen, a delegate at last week’s symposium. Mr Ineichen, who studies fireflies in Switzerland, said: “When you talk to old people about fireflies, it is always the same. They saw so many when they were young, now they are lucky to see one.”
Other delegates told similar tales. Fredric Venci, a researcher at Stonybrook University in New York, discovered a new species two years ago, only to learn that its mountain habitat in Panama was threatened by logging. Lynn Faust spent a decade researching fireflies on her farm in Tennessee, but gave up on one species because she stopped seeing any. “I know of populations that have disappeared on my farm because of development and light pollution,” she said. “It’s these McMansions with their floodlights.”
Evidence of fireflies’ demise remains anecdotal. Evidence has been difficult to gather, because there are few monitoring programmes. Counting the tiny, nocturnal creatures is a challenge, since the firefly’s adult lifespan is one to three weeks and some females spend most of it on the ground, or do not flash.
There are about 2,000 species, and researchers are constantly discovering new ones. Many have never been studied, and scientists know little about the potential threats to them, or about the meaning of their Morse code-like flashes, which signal anything from love to danger. Experts are turning to volunteers for help, asking firefly enthusiasts to report changes in populations in t.
Mr Preecha, the boatman in Bam Lomtuan, has seen the pristine river of his childhood become polluted and its fish disappear. Now he fears the fireflies will be gone in a year. He says: “Our way of life is being destroyed.”