Butterflies have always fascinated people. Their extraordinary wings have proved a lure to collectors for centuries. But as we approach a new millennium, we are now able to admire them in a far more sympathetic way than did our Victorian ancestors, who would assemble trays of exquisite specimens impaled on pins.

Butterfly farms are the environmentally friendly solution: large heated glasshouses where butterflies can be observed as close to their natural habitat as possible. The glasshouses are usually filled with tropical plants, splashing waterfalls, meandering paths and, of course, a multitude of butterflies.

You can expect to see up to 40 species at any one time, originating from the rain-forest regions of central and South America, east Africa, Malaysia, the Philippines, Thailand and Indonesia.

These butterflies have been farmed by local people, not captured in the wild. They are carefully nurtured and the pupae are luckier than their relatives in the wild, in that they can mature without the threat of parasitism from flies and wasps.

They are exported in their chrysalis state to livestock dealers around the world.

Of all the species at Edinburgh Butterfly and Insect World, the most admired must be the blue morpho (Morpho peleides) from Central America. This incredible creature has iridescent blue wings, five inches across, that appear to shimmer and glow as it sails effortlessly past.

The colouration is not due to pigment in the wing scales - arranged like microscopic slates on a roof - but to refraction. Minute ridges on the scale surface act like a prism, reflecting the blue part of the spectrum, giving rise to this amazing spectacle.

It is not uncommon to see a dozen of them, flying in bright sunshine in close formation. It just dazzles the eye, and for many of our visitors, it is an unforgettable experience.

Ian Mann Ian Mann is manager of Edinburgh Butterfly and Insect World, Dobbies Garden World, Lasswade, Midlothian EH18 1AZ. Tel: 0131 663 4932. Open daily