A radical environment group, the Earth Liberation Front, has claimed responsibility for setting fires to several houses under construction on what used to be farmland on Long Island, N.Y. The vandals left the message, “If you build it we will burn it,” in red paint on one house damaged on Saturday. The ELF, whose members are unknown, issued a news advisory on Sunday that said it was trying to boost costs to force “rich sprawl corporations” to stop developing Long Island. Although other environmentalists in the area disapproved of the group’s activities, they also criticized sprawl on the island. Richard L. Amper, Jr., executive director of the Long Island Pine Barrens Society, said, “Just because they are behaving like terrorists doesn’t mean we are not overbuilt.” The ELF in the past has said it was responsible for such environmental protests as setting fires at the Vail ski resort in Colorado to protest threats to lynx habitat.