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News article created on 22 August 2014

Weevil attack on the Huddersfield Broad Canal

A hungry army of 4,000 weevils has been released into a Yorkshire canal to help us tackle a troublesome water weed.

We've released the 2mm-long weed-munching weevils into the Huddersfield Broad Canal so they can eat the invading Water Fern (Azolla filliculoides). 

Azolla is a voracious grower and, if left unchecked, could cover the surface of the canal with a thick mat reducing light and oxygen levels in the water and causing problems for boats and anglers. Our ecologists are stepping in by releasing the weevils near Colne Bridge so they can munch their way through the weed keeping the canal healthy and clear.

Natural sollution

The weevils are an effective natural means of tackling Azolla and are at their most active at this time of year. They breed quickly so collectively they can eat their way through a very large mass of the water fern in just a few weeks. The weevils are known to feed exclusively on Azolla and don’t cause damage to other native species so are ideal for tackling the problem.

Phillippa Baron, ecologist for the Trust said: “Azolla might look attractive but it’s actually a serious threat to the health of the canal so it’s important that we step in and take action.

“Introducing thousands of weed munching weevils may seem like an extreme course of action but it’s been tried elsewhere and had great results so we’re looking forward to letting them loose on the Broad Canal”.

Azolla originates from the Americas but was introduced into the UK in the 19th century as an ornamental plant for garden ponds. The weed soon escaped and continues to cause problems on canals, rivers and lakes.

The weevils have been provided by CABI, an international organisation which aims to protect the environment and preserve bio-diversity.