With summer nearly upon us, a warning has been sounded over the effectiveness of ultrasonic repellers in warding off mosquitoes.
The Consumer Council said yesterday the repellers were unlikely to be totally effective against the 70-plus species of the insect found in Hong Kong.
The devices work by mimicking the sounds made by male mosquitoes and dragonflies in an attempt to frighten away the biting females.
But data provided by two of six local suppliers of the devices found mosquitoes continued to enter laboratory-controlled spaces where the products were in use.
There were relatively fewer mosquitoes in controlled spaces where the devices were in use, but the council said their efficacy in real-world environments was in need of further investigation. 'We do not have any concrete evidence showing ultrasonic mosquito repellers can prevent mosquito bites all the time,' said Ching Pak-chung, vice-chairman of the council's publicity and community relations committee.
While urging caution before completely writing them off, he said: 'Bear in mind that according to many scientific reports, their effectiveness is in doubt.'
