Kuala Selangor’s fireflies, known as kelip-kelip in Malay, are actually six-millimetre-long beetles of a kind found between India to Papua New Guinea. During the day, the fireflies rest on blades of grass or in palm trees behind the river’s mangrove swamps. After sunset they move to the mangroves themselves, the males attracting mates with synchronized flashes of light at a rate of three per second. Females flash back at males to indicate interest and initiate mating. The most successful males are apparently those that flash brightest and fly fastest.
Boats leave on 30min firefly-spotting trips from two locations several kilometres from town: Bukit Belimbing (run by Firefly Park Resort) on the north bank across the river bridge; and at Kampung Kuantan, on the south bank. It’s important to remain quiet when watching the firefly display and not to take flash photographs, as such behaviour scares the insects away.