How weevils have become weapons in UK’s fight against invasive plants

A weevil designed to kill a problem aquatic weed is the latest biological agent selected to tackle the economic and biodiversity scourge of invasive species in the UK

By Adam Vaughan

Housed in a plastic food container and measuring just 0.5 centimetres long, the weevil doesn’t look very menacing. Yet this specimen of Listronotus elongatus is the UK’s latest hope in a new wave of biological ways to control invasive species rather than using unsustainable chemical and mechanical methods.

The South American creature’s target is floating pennywort (Hydrocotyle ranunculoides), an invasive plant that chokes rivers and lakes by creating heavy floating mats, cutting water oxygen levels and outcompeting native plants.

The weevil I …