Tiny weevils deployed at Kew Ha-ha to tackle invasive water plant
6 August 2026 · By Boroughly editorial — AI-assisted, human-reviewed.
Richmond Council has released specialist beetles into the Kew Ha-ha waterway as part of a nature-based effort to control floating pennywort, an invasive plant that can choke waterways and crowd out native species.
Working with CABI (Commonwealth Agricultural Bureau International) and Royal Mid-Surrey Golf Course, the council introduced Listronotus elongatus — small weevils that feed specifically on floating pennywort — directly into the water. The project is funded by the council's Climate Change Steering Group and forms part of a wider push to reduce reliance on chemical herbicides across the borough.
The Kew Ha-ha presents particular challenges for conventional management: the site is hard to reach by hand, and tidal flows regularly bring fresh plant fragments back into the water, making manual clearance a losing battle. The weevils offer a cost-effective alternative that can work continuously without chemical intervention.
The beetles are not expected to eradicate the pennywort entirely, but should meaningfully slow its spread and limit its impact on the local ecosystem. The site will be monitored over the coming year to assess how well the weevil population establishes itself and whether it survives winter conditions. Further releases may follow if needed.
Full details are on the Richmond Council website.