Tansy bushes were accidentally cut down from the banks of the Selby Canal after markers used to identify the vital vegetation were moved without the knowledge of the Canal and River Trust.
The canal has been an ark site for the endangered Tansy beetle since 2015, when 50 captive-bred insects were relocated there following the discovery of a patch of Tansy growth upon which the species depends on for food.
Although there is a population of thousands of Tansy beetles along the River Ouse in York, they are considered highly vulnerable to a flooding event which could completely wipe them out. Selby Canal was chosen for the ark project because is it not flood-prone. The only other British habitat where the insects are found is in the Cambridgeshire Fens.
The beetles cannot fly, so struggle to colonise new areas if they face environmental pressures and they have consequently become isolated. The species was once common but has been severely affected by habitat loss, changes in land use and the spread of invasive Himalayan Balsam.
A spokesperson for the Canal and River Trust said: ""In 2015 Selby Canal was one of several ark sites in York selected by the Tansy Beetle Action Group (TBAG) to reintroduce and monitor the Tansy beetle. Canal and River Trust which looks after the canal has been supporting the valuable work of the group since 2017.
"We are very saddened that during a recent annual trim of the canal banks at Selby Canal we lost some of the habitat vegetation for the Tansy beetle population. Without our knowledge or consent the markers which we use to delineate this protected habitat were removed and inadvertently our contractors trimmed this area.
"With the vegetation cutback timed for the start of autumn, when Tansy beetle populations usually move underground, we hope that the impact will be limited. Our team will reinstate the markers so they are in place and prominent when the Tansy grows back next year to help recover this population. We aim to re-engage with local volunteers who will help us monitor and protect the area as restrictions allow.
"Our volunteers are vital in helping our charity look after its rivers, canals and reservoirs. We have really felt the impact of having fewer volunteers and members of staff frequently present on the canal during the pandemic. As our eyes and ears on the ground they make a huge difference in helping look after our canals and reporting instances like this."