SINGAPORE - Have dinner before the sun sets, keep the children indoors, and shut the windows - that is how some Housing Board residents at three Bukit Batok blocks are dealing with the swarms of black insects that have made a return after four years.

But even as residents are adjusting their daily routines, many are appealing to the relevant authorities to find a solution so the bugs do not return to haunt them again.

On Thursday (Oct 3), the town council stepped in with a series of measures that appear to have eased matters. But insect experts said a longer-term solution may lie in understanding the cause of the insects' resurgence, which could be linked to the weather.

For residents like Mr Bala Suppiah, a 48-year-old civil servant, he is taking no chances with the beetle-like critters when it comes to his children.

He has told them not to play at the void decks of the affected blocks - Blocks 170, 171 and 172 in Bukit Batok Avenue 8 - for the next few days.

"The situation is usually worse on the lower floors. My children are still allowed to play outside elsewhere but these three blocks are now out of bounds," he told The Straits Times on Friday.

This is the second time the black insects have plagued the three Bukit Batok blocks, although residents said it was a lot worse the first time, in 2015, as there were many more bugs affecting their lives for about three weeks.

For instance, residents would find only a handful of clumps - some the size of a dinner plate - of the dead insects at the void decks this year but there were easily more than thrice the number four years ago.

The winged insects had inexplicably appeared in large numbers on Wednesday after the sun had set. Their numbers have since fallen significantly, but many residents are bracing for the bugs to be around for a few more days.

Residents said the winged insects seem to be attracted to light and that many of them end up dead on the floor, leaving people to clear up the mess in the mornings.

One resident, who wanted to be known only as Madam Tan, said her 14-year-old son's revision for his examination was affected by the insects, saying: "They are noisy when they hit the window panes and walls, and leave a pinkish trace on our skin when they crawl on us. I'm frustrated that this is happening again."

The 39-year-old said she has lodged a complaint with the Jurong-Clementi Town Council.

In 2015, ST reported that the insects haunting the three blocks then were harmless beetles that did not bite as they had no "chewing parts". There is a high chance the flying insects this year are from the same species.

Mr Foo Maosheng, a scientific officer at the Lee Kong Chian Natural History Museum at the National University of Singapore, said he went to Bukit Batok to inspect the insects on Friday morning.

The 31-year-old, who helped with the identification of the beetles from the 2015 outbreak, said his first assessment is that the bugs this year are the same species from four years ago.

Mr Foo said the insects are attracted to light sources for navigation at night to find a mating partner.

Mr Sean Yap, a PhD student at the National University of Singapore specialising in beetles, agreed, saying: "For species level identification, we will need more information, but based on the photos and location it is likely another outbreak of Ataenius australasiae, a type of scarab beetle.

"Their larvae live underground feeding on roots of grass and emerge as adults to mate."

The 27-year-old said their sudden emergence could be due to environmental cues, such as the rain or a drop in temperature.

Mr Yap said: "It is possible that when it's raining regularly, the beetles' emergence is spread out. But now with the sudden rain after a pretty long dry period, they're all emerging at once. "

While last month was the driest and warmest September on record, the National Environment Agency has noted that Singapore has had showers in the past week and that a three-month dry period had ended.

The Jurong-Clementi Town Council, which manages the estate, said on Thursday that it has adopted similar measures to those taken in 2015 to deal with the insects, such as covering the lights at the corridors of the three blocks with yellow-tinted paper.

With the help of the Residents' Committee, the town council has also instructed residents to shut their windows and switch on fewer lights.

Because the land surrounding the affected blocks belongs to other agencies, the town council said it has contacted the National Parks Board and HDB to check for possible breeding sites of the black insects in these areas.

Mr Fang Rong Fa, who lives in Block 171, said the bad experiences he had four years ago has taught him how to deal with the insects this year better.

The 53-year-old, who works in accounting, said: "We just shut the doors and windows when the sun is setting now so (the insects) are kept outside our homes.

"They look dead because they just lie on the ground, but look at them again 10 minutes later and their positions have all moved."

Assistant manager Abby Lim, 40, who lives in the same block, showed ST the insect bodies outside her door on Friday afternoon, saying: "I wake up in the morning now to sweep so many of these insects off my doorstep. It's disgusting, and I just wish someone would tell us what is going on."