One of the rarest moths in the UK has returned to Derwentwater in the Lake District - after vanishing for nine years - thanks to the cows which graze the land.
© National Trust
The strikingly patterned netted carpet moth was first recorded in the UK in 1856 at woodland near Windermere in Cumbria. Since then it has been found at only a handful of sites in the Lake District and north Wales. In the 1980s there was widespread concern about a severe decline in numbers. The moth was last recorded at this Trust site in 1999.
The conservation challenge with the netted carpet moth relates to its total dependence on a scarce plant; touch-me-not balsam. Without sufficient balsam the future of the moth would be in serious doubt.
Research over the last 15 years by the Trust, the University of Reading and Butterfly Conservation, with funding from Natural England, has found that the balsam does not form a long-lived seed bank in the soil and will disappear from a site within two years if unable to set seed.
Traditional hardy cows have played a crucial role in creating the right environment for the balsam to flourish. The cattle have reduced competition from perennial plants by grazing and trampling, creating more open ground which encourages the annual germination of balsam seeds. Balsam seeds have also been transported by the cattle’s hooves, helping to creating new colonies.
John Hooson, National Trust Nature Conservation Adviser for the North West of England, said:
'We’ve been working closely with a farmer to introduce controlled winter cattle grazing, targeted in selected areas of woodland. This has really helped maintain and expand the Balsam colonies, particularly in areas where we know that there are moth colonies. As a result the moth population is now more robust and able to weather natural fluctuations.'
' It has been such a success that, in the seven years since the initiative began, the number of netted carpet larvae has risen from 12, found on 400 balsam plants, to over 1,000 found on 56,000 plants.
Success in managing the habitat and boosting moth numbers at Coniston has enabled a reintroduction project at Derwentwater to take place. In autumn 2007 work was carried out to try and re-establish the moth at a traditional site near Derwentwater. Survey work carried out this autumn found a small number of netted carpet larvae, meaning that the re-introduced moths had successfully survived and bred.
John Hooson, continued: 'The balsam is again thriving at this location but without our intervention the moth would never have managed to find its own way there.'
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