My battle to rescue Britain's magical butterflies, by Emilia Fox

The summers of my childhood were spent at our family's holiday house by the sea in Dorset. We would enjoy leisurely picnics on a rug in the long grass, and one of my fondest memories is running through the garden looking for butterflies.

I remember so clearly the feeling of exhilaration when I spotted a species of butterfly I had not encountered before. I would collect lilac buddleia for them to feed on and I would spend the evenings either recording newly noticed habitats or trying to paint these beautiful creatures.

And then one day my mother mentioned that fewer and fewer butterflies were appearing in our garden in summer.

Emilia Fox

Emilia hopes to turn her new home into a private flower and butterfly sanctuary

By this time, I had followed my parents - Edward Fox and Joanna David - into the acting profession and I was living in London.

I realised my mother was right: the magical creatures of my childhood seemed to have disappeared from our lives.

Concerned, I started to do some research. And what I found made terrifying reading.

A report last year by the charity Butterfly Conservation showed that of the 54 resident species of butterfly in the UK, 76 per cent are in decline.

This century, loss of butterfly species has outstripped those of birds and plants.

The number of butterfly species on the priority endangered list has more than doubled in 12 years, rising from 11 butterflies and 53 moths in 2005 to 24 butterflies and more than 150 moths in 2007.

Their decline is a silent tragedy that we give little or no thought to as we systematically go about destroying their natural habitats of meadows, wildflowers and grasses.

What is truly terrifying is that butterflies are such a valuable barometer of our environment - the first to go if environmental conditions are not well balanced.

Butterflies and moths are important to the ecosystem of every continent except Antarctica.

Butterfly eggs and caterpillars are a significant food source for other insects, frogs and birds. By chewing and digesting huge quantities of leaves, caterpillars cycle nutrients through the ecosystem. And butterflies are important plant pollinators.

Although I cared, I didn't know how to help. Then, by chance, I was introduced to lepidopterist Clive Farrell.

As my husband Jared Harris and I planned our wedding three years ago, a family friend asked us if we would like Clive to breed some butterflies for us to release as we left the church. We accepted immediately.

Emilia Fox and husband Jared release butterflies after their wedding in 2005

Wing and a prayer: Emilia and her husband Jared release butterflies after their wedding in 2005

After the ceremony, Jared and I were each handed a box. When we opened them, a stream of red admiral, peacock, brimstone and painted lady butterflies were released into the air. It was a joyous sight.

Earlier this year, the family friend told me about Clive's latest project - to create the world's largest sanctuary for butterflies.

Once completed in spring 2011, a 300ft-diameter glass biome in St Albans will be home to 10,000 tropical butterflies and 250 different species.

It will simulate temperatures and weather patterns from around the world so visitors can get a full tropical-rainforest experience, and it will have waterfalls and reproduction Mayan ruins that will soak up heat during the day and emit it at night so the butterflies can feel completely at home.

Elsewhere on the 26-acre site there will be 'antennae' walkways, a ' chrysalis' pond and a spiral 'proboscis' walk, each with specially selected nectar food plants to attract indigenous butterflies.

It is hoped that up to one million people will visit the centre every year.

At the moment Clive is concentrating on breeding the different species of butterflies, including the rare blue morpho, which is as big as your hand.

Money, inevitably, is a concern. The project is forecast to cost £25million, of which £14million has so far been raised.

Unfortunately, the centre has been denied Lottery funding, which I think is a travesty, so the remaining £11million is being raised through private sources.

Through Clive, my love of butterflies has been reawakened and I wanted to know what I could do to support their battle for survival.

Clive told me to plant buddleia, michaelmas daisies and lavender in my courtyard garden, to keep any existing holly and ivy, and to grow a half barrelful of stinging nettles because butterflies love all of these and plant their eggs in the hairs of the stinging-nettle leaves.

Although our butterfly population is in trouble, there is some good news: if we provide the right environment, they will thrive in our country once again.

I still spend a lot of time at our family home in Dorset. My father keeps the gardens wild so that nature can have free rein. My brother Freddie and I were brought up to respect and admire natural beauty and I hope one day to be able to instil that reverence in my children too.

Today, Jared and I have a home in Los Angeles. My dream is to turn it into our own private flower and butterfly sanctuary. Hopefully, it will be a garden that our children will cherish as much as I have cherished the wild paradise of my own childhood in the heart of England.