Help keep moth colony alive

When a moth so rare that there are only 15 known colonies in the British Isles was discovered in Oxfordshire two years ago, hopes were raised that this might not be the only time it would be found in the county.

A century ago the Barberry Carpet Moth (pareulype berberata) was widespread in England but is now an endangered species, chiefly as a result of the large-scale removal of its sole larval food plant, the common Barberry shrub (berberis vulgaris).

Its other known sites are mainly in Wiltshire, with colonies in Gloucestershire and Dorset and introduced colonies elsewhere, including in Suffolk, Lincolnshire and Northamptonshire.

Historically, the the most sighting in Oxfordshire was in 1992. Elsewhere in the world, it occurs in western and eastern Europe and from the southern-most parts of Scandinavia to the northern Mediterranean region.

The moth was given some legal protection under the Wildlife and Countryside Act of 1981, mainly to deter private collectors. It has been the subject of an English Nature Species Recovery Project since 1995 and conservation work has also been taking place as part of the UK Biodiversity Action Plan.

For the past two years, Butterfly Conservation has been sharing the co-ordination of this work. Although the general public cannot be actively involved, there is a way in which they can help, explained Butterfly Conservation's moth conservation officer, Kelly Thomas.

"The chief cause of the moth's decline is the loss of its food source," she said. "One of the things we are trying to do is to locate where there are barberry plants still growing in hedgerows.

"We are also trying to encourage the inclusion of the Common Barberry when planting of native species is taking place during hedgerow regeneration. This is quite a complicated project but we are trying to do our best to restore the numbers of this moth.

"Where there is barberry present, we hope to be able to establish new colonies there and the moth's future is looking more promising."

The best time to be looking for berberis vulgaris is in May, when its bright yellow flowers will be in bloom. It has spiny, ridged twigs and the flowers hang in drooping clusters. It produces red berries.

The reason for its removal in the 19th century was that it was found to be a secondary host for the fungus wheat-rust, with the result that farmers began to grub it out. Some bushes were still being taken up in the 1990s, although modern strains of wheat have been bred to be resistant to the fungus.

The plant may also have disappeared through neglect, as although barberry produces many berries, grazing, ploughing and other land use often prevent new plants establishing themselves.

If bushes are overgrown, they are less attractive to the moths. The highest densities of larvae have been found on bushes that are trimmed and, as a result, have a fairly tight growth form.

However, hedge-trimming at the wrong time of the year can have disastrous effects. In one instance, when a hedge was trimmed in late August and early September, just when that year's second generation of larvae were feeding, the losses were great. A better time is later, when birds have also benefited from feeding on the berries but before the next nest-building season begins.

Another adverse effect has been mechanised trimming of hedges.

The location of the recent sighting in Oxfordshire of the Barberry Carpet Moth is being kept secret. It was discoveredby Butterfly Conservation members who reported it to Martin Townsend, Oxfordshire moth conservation officer.

Martin said: "They took a photograph and identified it by comparing it with a picture in a field guide, saw how rare it was and thought they surely couldn't have a Barberry Carpet Moth - but they had. Consequently, we have been encouraged to make more surveys."

In colouring, the Barberry Carpet Moth has forewings that are greyish and brown, with two black lines on the basal half and dark-edged, tooth-like markings towards the wing tip. The caterpillar is either grey or red but both colourings have a distinctive lengthways white stripe at the lower end.

It seems reluctant to feed on much growth other than that of its favourite Common Barberry. It has not so far been recorded on any cultivated species of berberis, some of which are often planted by landscapers in town gardens.

In cultivated colonies, however, adult female moths have laid eggs on species such as berberis thunbergii and berberis ottawensis and the larvae have fed on some of the species with soft, fleshy leaves.

There is encouragement, however, for the most important species, berberis vulgaris, to be more prevalent.

The UK Woodland Grant Scheme and the Countryside Stewardship Scheme are helping to achieve more planting. There are now sites judged ready for trials.

These attempts at increasing colonies involve removing minimal numbers of adults or larvae from existing populations and then breeding to provide much larger numbers for release on to established sites.

The conservation also includes close liaison between site owners and conservation teams to advise on pruning, usually biennially, to promote tight growth form.

The planting of bushes to increase suitable habitats is beneficial and at several sites a programme of propagation from cuttings and seeds has been under way. New bushes have been planted to replace those lost over the years.

It is also essential that leaf-litter and ground beneath occupied barberry bushes is not disturbed and that there is no spraying with any fungicides, insecticides or other chemicals.

Any mowing of grass under bushes needs to be timed to take place outside the pupation and adult emergence periods of the moth, covering early May to mid-September.

Kelly Thomas recently held an information meeting in Buckland at which Butterfly Conservation members were joined by landowners and others with an interest in wildlife and the countryside.

The fact that the Barberry Carpet Moth has been seen in Oxfordshire indicates that this is a part of the country where its presence could be encouraged.