Many eggs and caterpillars were washed away or covered in deep water. One of the worst affected seems to be the Grayling, already down to a single known site on the Yorkshire Wolds and a handful of brownfield sites around Wakefield and Middlesbrough.

There is at least a little good news in that the county's two rarest butterflies, the Pearl-bordered Fritillary and the Duke of Burgundy both appear to have largely completed their breeding cycles before the weather broke. They were formerly more widespread but are now found only on the North York Moors. Conservation work by volunteers, organised by Butterfly Conservation in conjunction with the National Park, the Forestry Commission and other bodies, seems to have brought the steady disappearance of these species to a halt.

The next phase of an ongoing project will be to try to extend suitable habitats and build up numbers: a challenging task.

Butterflies fit into three main categories: the migrants that fly huge distances like the Red Admiral which comes from southern Europe every year; the wanderers that can readily fly a hundred miles or more like the Small Tortoiseshell and Peacock, and the specialists, like the Pearl-bordered Fritillary and "the Duke" mentioned above.

The first two groups survive because they can go long distances in search of suitable habitats. The specialists may only fly a few metres from where they were born, and will avoid having to fly far over any wide-open space like a field of crops, or over a block of tall trees, or through any dense shade.

So as habitats get split up or overgrown, these butterflies become more and more isolated. That can readily lead to genetic isolation, disease and extinction. Most butterflies need open but sheltered grassland between suitable habitats: the grassland to provide nectar plants for energy; and nearby trees and shrubs to reduce the effects of cooling winds.

Field margins are proving very helpful to some species, and Small Tortoiseshells, Peacocks and Wall Browns have been seen using these as pathways across open countryside, especially where hedgerows provide protection from winds.

Unfortunately, nationally and locally, we are close to losing all the butterfly species which cannot fly any distance. And some of our long-time resident species like the Common Blue, Small Copper and Wall Brown are dropping back to worryingly low populations. At the same time, we are gaining other species formerly confined to the South, which are now spreading rapidly north, such as the Comma, Holly Blue and Speckled Wood. All would benefit from a drier, sunnier summer than last year.

Governments across Europe are increasingly turning to butterflies as key indicators of what is happening in the wider world. Miners once used canaries as indicators of the health of the atmosphere below ground. Butterflies are seen as the canaries of the natural world. Their presence or absence is a clear indicator of the health of any given habitat.

Governments rely on the regular monitoring carried out by amateur naturalists and the general public. In Yorkshire alone, we have some 500 regular contributors who walk along tracks and paths open to the public, and record and map reference what they see. They do it for enjoyment and for the satisfaction of knowing that their efforts help to guide conservation effort and funding to where it is most needed. In the last four years Yorkshire recorders have produced 132,000 butterfly records. The organisation behind this work is the national conservation charity, Butterfly Conservation (BC), which aims to do for butterflies what the RSPB does for birds. As a national organisation BC is celebrating its 40th birthday.

Among many projects it hopes to develop further is the one to improve the lot of Yorkshire's two rarest butterflies, the Pearl-bordered Fritillary and the Duke of Burgundy.

BC operates through semi-independent regional branches which not only monitor their local butterflies but also work with national parks, and major landowners like the Forestry Commission and wildlife trusts to help and advise on butterfly management issues.

The Yorkshire Branch also runs two small butterfly nature reserves, one at Shipley railway station and the other in association with the Yorkshire Air Museum at Elvington, near York.

The branch was founded in 1981 with 13 members. Since then it has grown steadily to more than 700 members today. Yorkshire butterflies have been monitored by the YNU on a regular basis since about 1875, but the detailed coverage was only launched in 1995 as a joint BC/YNU response to helping to produce the national butterfly atlas published in 2001. By the previous year Butterfly Conservation, Yorkshire had accumulated so much valuable information about the county's butterflies that it was decided to produce a Yorkshire book. More than 30 volunteers took part in what turned out to be a mammoth task in researching the distribution and histories of no fewer than 62 butterfly species which have reportedly been recorded in Yorkshire since the 1780s.

Thanks to generous sponsorship from many sources, the branch has produced a full-colour, 312 page paperback with more than 400 coloured paintings, photos, maps and diagrams, all provided by volunteers.

The branch was particularly fortunate in having a first class artist, Nick Lawman, among its ranks, and he provided paintings of all our 35 regular species.

The book has been hailed by national experts as setting new standards for regional butterfly books.

Each one of the county's
35 regular butterfly species
is given five pages each, with colour-coded sections to enable easy reference, while the remaining 27 rare or extinct species are detailed according to the information available.

One of the book's unusual features is a four-page chart summarising 200 years of weather, season by season, and showing how swings in climate have affected the county's butterflies. This is supported by a fascinating introductory chapter on the extremes of Yorkshire's weather over that period and the way volcanoes in distant parts of the world may also have affected the success of some of our local species.

Another chapter looks at the way Victorian industry spread smoke and gloom over the West Riding and almost wiped out the butterflies of that region altogether.

The work of monitoring our butterfly populations continues to be an important means of studying how climate change is affecting our region.

BC Yorkshire places all its records on a national database available to Government and decision makers as well as researchers. It also produces annual reports for those participating.

More volunteers are required to help us cover every corner of the county. At present there are gaps in our coverage which readers might be able to help us with: 1) the high areas to the south west of Sheffield,

2) the Vale of York between York and Northallerton and in and around Northallerton itself,

3) The Vale of Pickering (the area between the North York Moors and the Wolds) and the nearby Howardian Hills,

4) The more isolated parts of the North York Moors and the Dales.

In addition, we get very few records from the urban parts of Bradford, Leeds and Sheffield where reports from gardens, parks and any wastelands – important places for butterflies – would be most appreciated.

Volunteers need to be able to identify the commoner butterflies and to read map references from Ordnance Survey maps. We provide special recording forms.

Howard Frost is voluntary County Butterfly Recorder for Butterfly Conservation (BC) in Yorkshire. He oversees the county's recording work, which is divided into five sub-regions each with its own co-ordinator. He also edits BC's Yorkshire Branch magazine Argus and an annual Lepidoptera Report for the county.