To outsmart rats, pest controllers are arming themselves not just with glue boards and traps, but also a range of equipment such as motion sensors and infrared technology.
Rats are intelligent and can adapt to urban spaces, so pest busters say that conventional methods may no longer be sufficient to hunt them down, which is why the rodent population seems to be growing.
So they are relying on gadgets which can help to better track down the rodents' movements, especially if they are hiding in structural gaps or building crevices.
The Norway or sewer rat, for example, traditionally lives in underground sewers or burrows, but can now be found living in gaps in or between structural defects.
For the past two years, Star Pest Control has been using an infrared motion detector to more accurately detect where the rats are hiding.
Its general manager, Mr Bernard Chan, said the device, which can be placed on top of places such as false ceilings, takes photos and videos of
pest activity to provide more clues on where the rat burrows may be.
"If I suspect there is pest activity in a certain area, I can place the detector there and then decide... if I should place a trap there or seal up the hole," said Mr Chan, whose pest-control firm was involved in the Bukit Batok rat infestation clean-up last December.
The weather-resistant device costs about $1,000 and has helped to improve the firm's productivity rate by 60 per cent, said Mr Chan, whose company has caught more than 500 rats this year.
Another company, Origins Exterminators, has jointly developed a motion sensor with technology firm Cre8tec.
The sensors - which are attached to existing devices, like glue traps or glue boards - are designed to map out "hot spots" which can track rats' movements from point to point.
"The traditional method is to look for signs of rodent activity and, in many instances, this means that gaps and other structural defects may hide the signs that pest managers typically look for," said Cre8tec director Deanne Baptista.
An SMS or e-mail alert is also sent out whenever rodent activity is detected, reducing the need for manpower.
Professor Rudolf Meier of the National University of Singapore's Biological Sciences department said that using infrared technology could be a good way to monitor infestation and avoid "misdirected pest control".
"Rats are known to learn fast and there is evidence that they will avoid, for example, poison," he said.
"The result is rats that are hard to control."
Based on figures from the National Environment Agency, there were 4,106 complaints received about rats last year, about 35 per cent more than in 2013.
The number of rat burrows also went up - with its inspections of public areas in October and November last year uncovering about 10,000 rat burrows, up from 6,400 burrows in the same period in 2013.
Improper storage and disposal of food waste could be one cause of infestations, said the agency.