Butterfly experts from 31 countries are meeting at Laufen, Germany.
At the meeting it was confirmed that the Maderian Large White has suffered global extinction, the first European butterfly to become extinct since the 17th century when records began.
Countries with intensive agriculture like Luxembourg, Belgium and the Netherlands were worst based on the number of species which have declined seriously or become extinct. Although the problem was reported throughout Southern Europe.
Changing farming practices throughout Southern Europe are causing concern. The meeting also heard stories from Bulgaria where internationally important butterfly sites are being destroyed along the "Silver Coast" to make way for tourist resorts, ski development, and golf courses.
There has been awareness of the problem in Britain for many years. Its 40 years since naturalist formed the charity Butterfly Conservation.
Martin Warren, Chief Executive of Butterfly Conservation and Chairman of Butterfly Conservation Europe, said:
"More and more countries are adopting improved ways of recording butterfly numbers, and there has been improved analysis of existing data, using methods pioneered in Britain. This new data points to a very serious problem."
"Patterns of butterfly behaviour are already telling us much about global warming and climate change. They are not just beautiful - they are going to be increasingly important."
Conservationists are trying to get the EU to acknowledge butterflies as indicators of what is happening to biological diversity - as England and Scotland already do.
You have to ask what are we doing to our world?