Fears of an explosion in the number of mosquitoes carrying potentially fatal dengue fever have prompted authorities to trial a new device aimed at stopping them from breeding in roadside drains.
The Highways Department is testing an American-designed contraption that will allow water and solid waste into the drain system while preventing mosquitoes, other insects and odours from escaping.
Some people are concerned existing roadside drains, which allow water and waste to gather at the bottom of a concrete sump, called a gully, provide a perfect breeding place for the dengue-carrying mosquito, Aedes Albopictus.
A spokeswoman for the Highways Department, which supplies and maintains the roadside gullies, said they were designed to keep larger bits of waste out of the storm-water system.
The department's chief concern was that the system still needed to be able to drain well.
The new gully inlet trap, slots into the top of existing gullies and is currently being tested on Cheung Chau and in Sha Tin and Causeway Bay.