KUALA SELANGOR, Malaysia (Reuters) - Malaysia's most famous insects, a colony of fireflies that blink like Christmas lights, top the list of wildlife hit by a thick haze of pollution from Indonesian forest fires.

For many visitors, no trip to Malaysia is complete without a star-lit canoe ride to see the twinkling fireflies near the mouth of the Selangor river, but some residents fear memories could soon be all that remain of the insects.

"At one time the tourists waited for the boats, but now the boatmen wait for the tourists," said Mokhtar, 55, who ferries visitors by canoe each night to glimpse the tree-dwelling fireflies and earns ten ringgit ($3) per trip.

"Tonight I fear I may get only one boatload of visitors."

The haze dampened the light-emitting mating ritual of the fireflies, an attraction that draws thousands of visitors a year to the seaside town, 65 km (40 miles) northwest of the capital and where the Selangor river flows into the Malacca Strait.

"They are the most popular firefly colony in southeast Asia, in terms of accessibility and the impact of their synchronised flashing, so they become an eco-tourism draw," said Andrew Sebastian, of the Malaysian Nature Society, which manages a nature reserve nearby.

But this year the haze discouraged the fireflies -- which are, in fact, beetles -- from twinkling as much as usual, said Mokhtar. "The fireflies were there, but they were less energetic," said the boatman, who gave only one name.

"Visitors who were seeing them for the first time did not know what they were missing."

Naturalists said firefly numbers had hit their lowest level in five months, but warned they did not know enough about the factors in the insects' lifecycle to pin the blame on the haze.

"We have noticed a drop in the firefly population," Laurence Kirton, a biologist with the Forestry Research Institute of Malaysia, who has been closely monitoring the insects for the last five months, told Reuters.

Kirton, who has spent three years studying the fireflies, did not say how much the figure had dropped, but felt park officials' estimates of about 50 percent were not too far off the mark.

Smoke carried by the smog is an irritant to insects, and carbon dioxide gas given off by fires is toxic, Kirton added. But he could not rule out factors such as a shortage of snails, the food of the young firefly larvae.

"Any insect population may have a cycle of abundance depending on the weather or the availability of food, or other factors, in its lifecycle," he said.

Scientists have not yet identified all the influences on the lifecycle of the firefly, a species they call Pteroptyx tener.

The chemicals in the haze could hurt animals and plants as well.

Plants rely on insects to reproduce by spreading their pollen grains and insect activity dampened by the haze could delay the pollination of flowering plants, Sebastian said.

The haze would also disrupt the migratory journeys of birds seeking warmer climes as the northern hemisphere winter nears.

"Birds coming from as far as Russia, Siberia and Japan are faced with the haze after flying thousands of miles to get here, so we fear for them," Sebastian said.

"If they depend on particular landmarks that are hidden by the smoke, they could crash and burn."

At the nature reserve, home to 150 species of birds and innumerable animals, a troop of long-tailed monkeys squabbled over fruitpods and a monitor lizard watched from its hiding-place in a shrub while a kingfisher swooped to the glimmering surface of a lake to seize an insect and fly off.

But the impression of normalcy could be misleading.

"Before the haze I used to see the golden-backed woodpecker often, but after the haze began I haven't seen it once," said park official Mohamed Aznizam. "Maybe it's hiding somewhere."