More than 100 entomologists and biologists attended a symposium in Thailand recently on the "Diversity and Conservation of Fireflies." Experts believe that firefly populations around the world are dwindling, the Associated Press reports.

The evidence is "anecdotal," reports AP environmental writer Michael Casey, who writes: "From backyards in Tennessee to riverbanks in Southeast Asia, researchers said they have seen fireflies — also called glowworms or lightning bugs — dwindling in number."

The nocturnal insect is so small and its adult life span so short, scientific evidence is hard to come by. Try tagging a firefly. But experts say the bugs may be hampered by urban sprawl, industrial pollution and artificial lights — the latter disturb mating patterns.

Apart from the beauty, charm and mystery of the insects, scientists are intrigued because they think the fireflies' situation may signal something amiss in the ecosystem they inhabit.

Certainly the luminous creatures are one of the ephemeral joys of summer, delighting children and adults alike. Collecting lightning bugs in jars on a summer night is one of childhood's enduring pastimes.

May they shine on.