Bjorn, aged five years, posing with a pair of owl butterflies during an event yesterday to launch the Sensational Butterflies exhibition at Britain's Natural History Museum in London.

The exhibition, which opens today and ends on Sept 11, features hundreds of moths and butterflies - including elegant swallowtails and iridescent blue morphos - flying freely among fragrant fruits and flowers.

Each year, hundreds of tropical chrysalises are flown from all over the world to the museum, where the insects then undergo metamorphosis to become adult butterflies.

Visitors have a rare chance to watch them develop and wander among fluttering beauties that are ethically sourced from countries in Africa, South America, North America and Asia.