A leading charity has put on hold its application to build a holiday camp in Tuen Mun after butterfly enthusiasts said the construction would affect up to 40,000 butterflies that migrate there every winter. The Tung Wah Group of Hospitals applied to build a 400,000-square-foot campsite in Siu Lang Shui, but a few days ago it asked the Town Planning Board to put the application on hold, the board said. At a press conference on Saturday, the Hong Kong Lepidopterists' Society said the campsite was just 200 metres from Hong Kong's biggest butterfly wintering site, which attracts between 10,000 and 40,000 butterflies from southern China every year. The society had also recommended to the Agriculture, Fisheries and Conservation Department that the site be designated one of 'special scientific interest'. If approved, it would be the first such site in the West New Territories. The Lepidopterists' Society chairman, Lee Ping-chung, said the department had agreed last year to give Siu Lang Shui the special status - among seven applications. But it told him this year that the designation could not be processed until next year. Dr Lee said even though the department knew Siu Lang Shui was a potential candidate, it told the Town Planning Board it would be acceptable to build a campsite there. A department spokesman said it had no objection to Tung Wah's plan, saying the proposed site and the butterfly wintering area were separated by dense woods. 'It would be unlikely to pose any significant disturbance on the wintering site,' he said. Dr Lee said the construction would change the environment and severely affect the butterflies because the trees they live in would be cut down. He said it was still a mystery why the butterflies returned to the same site every year. 'It might be the fact that the site has a hill behind it and it's facing south,' the society chairman said. 'That would stop the chilling wind from the north.' He said the environmental-impact assessment report on the site, which Tung Wah submitted to the Town Planning Board with its application on June 9, did not mention its proximity to the butterfly site. A spokeswoman for the Tung Wah group said they believed the camp would have no direct impact on the butterflies. She said the group would minimise the construction activities during winter, and only 11 trees would be affected. Their loss would be offset by planting more native species and improving the environment there. Before the group deferred its application, it was expected the board was going to approve construction at a meeting on July 29. Hong Kong has more than 240 types of butterflies and eight areas have been identified as major sites hosting wintering butterflies. The other seven sites attract only several thousand butterflies each year, according to the Lepidopterists' Society.