Conservationists are hoping the large blue butterfly's successful return to the UK - will continue this year with a new record for numbers flying at National Trust's Collard Hill .
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The large blue had vanished from the British countryside by 1979, but a successful reintroduction project over the past 25 years has seen it return to 25 sites, including the National Trust's Collard Hill near Glastonbury, Somerset where it was brought back in 2000. Last year a record 827 large blue butterflies emerged and flew on the National Trust site - a 22% increase on 2008, which in turn had been a record year.
The location has seen a strong increase in numbers over the past few years and with an estimated 20,000 eggs laid last year, the Trust is hoping for another ''bumper'' year for the insect. Matthew Oates, conservation advisor for the National Trust, said: ''The population is building well. The question is how big can this population get and the answer may well be very big by large blue standards. It's very exciting.
''We're expecting the population to increase further this year, and hopefully much further, but so much depends on the weather when the butterflies are flying.''
The large blue, like other butterflies, does better in sunny, settled weather, while cold, rainy conditions stop them flying.
The seeds for the potential success this year at Collard Hill are down, according to Mr Oates, to the ''excellent condition'' of the habitat provided for the butterfly and the ants it relies on for the more bizarre part of its life cycle.
The large blue begins life as a caterpillar feeding on wild thyme flowers, before tricking a species of red ant into thinking it is a lost ant grub so that it is taken into the nest, where it feeds on the actual grubs for 10 months before emerging as a butterfly. The species only thrives on dry grassland where wild thyme or marjoram and the red ants are found.
Rob Holden, National Trust area warden, said: ''The last four years at Collard Hill have seen a steady but strong increase in the number of large blue butterflies recorded. ''Getting the habitat in the right condition for this very particular butterfly has been crucial, and that has been down to getting the grazing right - using cattle and Dartmoor ponies.''
And the success of the butterfly at the site could mean other populations becoming established nearby, Mr Oates suggested.
More:
http://www.telegraph.co.uk/earth/wildlife/7786404/Blue-butterfly-successfully-reintroduced-in-Britain.html