Polystyrene balls are being used in a bid to prevent mosquito swarms biting hundreds of east London residents.
The mosquitoes have been breeding in water beneath tanks
The insects are breeding in water beneath tanks at sewage treatment works in Beckton, east London.
Some nearby residents have slept under mosquito nets to avoid being bitten by the insects during the summer.
Thames Water said it will sprinkle the balls over the water to "prevent the mosquitoes from getting airborne and subsequently asphyxiate them".
'Bitten a lot'
The mosquitoes in Beckton and neighbouring Barking are not thought to be the type that carry malaria, nevertheless they have become a pest to residents.
Maria Polly, from Beckton, said: "Usually between April and October, once the mosquitoes are out, we sleep under a mosquito net because otherwise you get bitten quite a lot at night."
Thames Water has sprayed the water chamber containing the insects with chemicals and believes the mosquitoes have been eradicated "for the time being".
Nevertheless, following expert advice, they are also sprinkling the balls onto the water to prevent further hatchings.
"We hope to have this control in place as soon as possible," a Thames Water spokesman said.
The experiment is being monitored all summer, and its success or failure is set to become evident next year.