A fern-eating beetle is the latest weapon in the war against alien plant life threatening British species

A plague of weevils are being used in the fight against a particularly problematic North American water weed that has taken hold in a Somerset canal.

British Waterways will release 5000 2mm-long weevils into the Bridgwater and Taunton canal at Maunsel Lock, which it hopes will eat the invasive water fern, also known as fairy moss and floating water fern.
 
Although individual water fern plants are only around 10mm long, they are voracious growers and can multiply rapidly, covering the surface of a waterway with thick brown mats (see picture) in a matter of weeks.

This reduces light and oxygen levels in the water, killing fish and other wildlife.

Robert Randall, a BW ecologist, explains, “Water fern was first introduced to the UK by the Victorians as an ornamental plant for ponds. Despite looking nice, this weed is actually a serious threat to waterway wildlife in the UK.
 
“The weevils breed extremely rapidly and only eat water fern so are very effective in destroying the plant without causing further damage to other species.”

“If we don’t act now there is a danger that birds may inadvertently transfer the weed to the rest of the canal. Then it will be much harder to contain the spread.”
 
Last year, BW spent more than £400,000 on clearing aquatic weeds from the 2200 mile network of canals, rivers, reservoirs and lakes that it cares for.

Many of these invasive weeds are freely available to buy as ornamental water plants in garden centres across Britain and can be transferred to the waterways if they are not disposed of properly.

Robert advises: “If you already have these plants in your garden, don’t put them down the drain or in the rubbish. Instead, compost, burn or bury them.”