Building work has started on a £25m conservation centre in Hertfordshire which will house thousands of insects.
Actress Amelia Fox was due at the site in St Albans to mark the start of construction work on Butterfly World.
The project was launched in March by Sir David Attenborough who said three-quarters of UK butterfly species had declined in the past 20 years.
Work will begin with construction of an eco-friendly access road to the site lined with hedge scrubs and trees.
The 26-acre site will be developed into the shape of a butterfly with a dome as its eye.
It will incorporate underground caverns featuring tropical creatures, including scorpions and spiders, and there will be more than 10,000 tropical butterflies in flight at any one time in the walk-through centre.
Butterfly expert Clive Farrell, who has developed the project, said: "Butterflies are like the canaries in the coal mine. When their environment is under stress, they are the first to suffer and disappear."
Organisers hope the site will attract up to one million visitors a year when it opens in 2011.