Invasive beetles that have infested maple trees in U.S. cities could pose a threat to New England’s iconic hardwood forests, a new study says. While earlier outbreaks of the Asian longhorned beetle have occurred on tree-lined streets in city neighborhoods, including in Chicago, New York and Boston, the study by U.S. researchers says the pests could disperse into natural forest landscapes. While the insect feeds on numerous types of hardwood trees in urban areas, in forests it disproportionately attacks maples, researchers say. In 2008, scientists first detected the beetle in Worcester, Mass., a city surrounded by heavily wooded forest that is part of a corridor stretching from New York to Vermont and Maine. Since then, foresters have established a 98-square-mile containment area to prevent the spread of the beetle. “The [beetle] apparently has been in the Worcester area for at least 10 years, and, undetected, could have easily spread to even larger tracts of continuous forest,” said David A. Orwig, a forest ecologist at the National Science Foundation’s Harvard Forest Long-Term Ecological Research site and co-author of the study, published in the Canadian Journal of Forest Research.