AN unusual ally has been enlisted to combat a fast-growing and invasive plant in a Boston waterway.
The Environment Agency has released thousands of tiny weevils into the Maud Foster Drain near Cowbridge in an effort to reduce the volume of Azolla growing there.
Also known as the fairy or water fern, Azolla can double in size every four to five days forming dense mats up to 30cm thick.
It can cause damage to riverbanks, increase flood risk and crowd out or kill off native wildlife.
Debbie Sylvester from the Environment Agency said: "Azolla grows extremely quickly and can completely cover the water's surface.
"These weevils eat only this plant and should help to control its spread."