Branch is devoted to an insect

Save our Butterflies Week may be taking place from July 21 but for supporters of the Butterfly Conservation it is a year-round mission. One of the largest local branches is the Upper Thames region and its members will contribute to the national event with an open day next week.

Events and publicity committee chairman Frank Banyard describes it as a "beginners, butterflies for all, and children's event", being held in the Holtspur Valley, near Beaconsfield.

"The reserves should be at their best," said Frank. "If you are not yet confident in identifying our butterflies and day-flying moths, this is for you."

The Upper Thames branch was founded in 1982, when around 20 people attended a meeting in Oxford. Since then it has grown to become one of the largest and most active of the 32 throughout the country, with a membership of more than 600.

National membership totals around 12,000 and Butterfly Conservation is considered to be one of the largest organisations in the world devoted to a single species of insect.

The emblem of the Upper Thames branch is the marbled white butterfly, an established inhabitant of its reserve.

"Once seen, never forgotten," is how Frank describes it. "It is typical of the area and very much a butterfly of the Chiltern Hills and up into the Cotswolds and can even be seen in the centre of High Wycombe. We felt it was an appropriate choice."

Around 30 species have been recorded at the Holtspur Valley reserve around half of those to be seen in this country some regular inhabitants, and some occasional visitors. Up to 200 species of moths have been recorded there during flight seasons.

The branch has a Countryside Stewardship grant to help towards returning the reserve to meadow grassland. To enable the wild flowers to compete successfully with the coarser grasses, the reserve is either mown, three times a year, or grazed by visiting flocks of sheep.

For a number of species of particular interest or rarity, a member acts as 'species champion', to co-ordinate all information that comes in relating to colonies recorded at various locations throughout the area.

There are more than 20 'transects', a route walked regularly and all information about butterflies or moths within two-and-a-half metres on either side noted for comparison with previous recordings.

"This provides a regular means of seeing how species are doing year by year, whether numbers are up or down, and give us a means of assessing how the butterflies are faring," explains Frank Banyard.

"Unless we know how our own conservation work is affecting population, we cannot tell whether what we are doing is right."

Late autumn and winter are the times of greatest activity in conservation work, which involves clearing excessive scrub on downland, opening up of over-dense woodland and tree planting work which cannot be done during the flight season of the butterflies and moths.

The peak of flight activity is between April and October, although occasional sights of some species may occur in mild spells in any month of the year.

During the flight season, the key activity is recording the numbers and locations of species, information which helps in planning conservation.

As a means of identifying unfamiliar species, recorders have the benefit of being able to consult their own 'Butterfly Atlas' Butterflies of Berkshire, Buckinghamshire and Oxfordshire which was produced by members. The first edition was in 1985 and a new edition is about to be published.

Not all recording, however, is of the most easily spotted. The butterflies and moths are at their most colourful and dramatic when in summer flight.

Branch chairman David Redhead said: "I feel that the more we can learn about the ecology of our butterflies and moths at all stages through their life cycle, can only make our work more valid.

"Understandably, most of our effort goes into observing the adults, owing to their visibility, beauty and the fact that they are active during the warmer months of the year. However, in practice, the distribution and abundance of species is predominantly dictated by the requirements of the other life-stages and especially those of the larvae.

"From my own experience, the other life-stages have a fascination and beauty of their own and observation of these can be equally rewarding."

Earlier this year, members were out and about observing two of these stages. In February, a day was spent at the RSPB reserve at Otmoor to look for and tag eggs of the brown hairstreak butterfly. This was followed in May by a 'Caterpillar Crawl' to look for the caterpillars that had emerged from these eggs.

Another springtime visit was to the BBOWT reserve at Moor Copse, near Pangbourne.

"Butterfly Conservation has a range of its own reserves throughout the country, but our major policy is to work in conjunction with other conservation bodies," said Frank. "We also work with landowners and private individuals to improve the habitat."

The Upper Thames region has a large proportion of the colonies of the black hairstreak butterfly, the 18 colonies in Oxfordshire and the same number in Buckinghamshire together representing some 70 per cent of the national total.

The brown hairstreak was known to have a colony to the north-east of Oxford, but its 'species champion' David Redhead was pleased to receive news of sightings just south of Wheatley and on blackthorn alongside a footpath in Marston, making it, he said, "a resident of the city of Oxford".

Blackthorn is a shrub important as a food for a number of species and also benefits other wildlife in providing a nesting site and winter food for birds.

Many butterflies and moths feed on only one plant at either the caterpillar or flight stages of their life-cycle so it is a case of no food source, no butterfly.

Among these specific needs are that of the small blue butterfly for kidney vetch, of violets for the larvae and knapweed for the adults of the dark green fritillaries and sheep's fescue for the silver spotted skipper.

The drab looper moth feeds on wild thyme and the striped lychnis moth on the tall spikes of the dark mullein.

Oak and ash trees are also beneficial to the black and brown hairstreaks for they feed there on the honeydew secretion of aphids.

Among the functions of Butterfly Conservation is commenting on planning applications which might have an adverse effect on wildlife.

Activities are not limited however to the Upper Thames region, for they frequently visit branches in other areas of the country to observe butterflies and moths, and indeed venture further afield, such as on a recent visit to the Pyrenees.

The branch's open day on Saturday, July 15, iin the Holtspur Valley is on their own Holtspur Bottom Reserve and the neighbouring Holtspur Bank Local Nature Reserve, between 10.30am and 4pm.

There will be walks on both reserves during the morning and afternoon and an afternoon walk focusing on plants. In the Scout Hut in Cherry Tree Road, off Holtspur Top Lane, there will be a series of displays.

Other events for Save our Butterflies Week will be on the following Saturday, July 22, from 10.30am to explore the heathland and other habitat types at Greenham Common, near Newbury, in a joint event with the Hampshire branch, and at Watlington Hill on Thursday, July 27, between 2pm and 4.30pm, with a good range of summer butterflies to be seen.

There are walks too at Aston Rowant National Nature Reserve, held jointly with the Warwickshire branch, to look for downland butterfly species, on Sunday, July 30, from 10.30am.

Enquiries about membership and events held by the branch can be made to Frank Banyard on 01494 672310.