removal, insecticides, and biological control are used to reduce damage to ash trees. Quarantine and tree removal Once an infestation is detected, quarantines are typically imposed by state, or previously, national government agencies disallowing transport of ash firewood or live plants outside of these areas without permits indicating the material has been inspected or treated (i.e., heat treatment or wood chipping) to ensure no live emerald ash borer are present in the bark and phloem. In urban areas, trees are often removed once an infestation is found to reduce emerald ash borer population densities and the likelihood of further spread. Urban ash are typically replaced with non-ash species such as maple, oak, or linden to limit food sources. In rural areas, trees can be harvested for lumber or firewood to reduce ash stand density, but quarantines may apply for this material, especially in areas where the material could be infested. Kentucky Extension specialists suggest selecting uncommon species to replace removed ashes in the landscape. Previous generations created monocultures by planting ash trees in an overabundance, a factor in the extent of the devastation caused by the emerald ash borer. Favoring instead a diversity in species helps keep urban forests healthy. University of Kentucky scientists suggest choosing monotypic species such as the pawpaw, yellowwood, Franklin tree, Kentucky coffeetree, Osage orange, sourwood, and bald cypress. Insecticides Insecticides with active ingredients such as azadirachtin, imidacloprid, emamectin benzoate, and dinotefuran are currently used. Dinotefuran and imidacloprid are systemic (i.e., incorporated into the tree) and remain effective for one to three years depending on the product. Insecticides are typically only considered a viable option in urban areas with high value trees near an infestation. Ash trees are primarily treated by direct injection into the tree or soil drench. Some insecticides cannot be applied by homeowners and must be applied by licensed applicators. Damage from emerald ash borer can continue to increase over time even with insecticide applications. Insecticide treatments are not feasible for large forested areas outside of urban areas. Biological control The native range of emerald ash borer in Asia was surveyed for parasitoid species that parasitize emerald ash borer and do not attack other insect species in the hope they would suppress populations when released in North America. Three species imported from China were approved for release by the USDA in 2007 and in Canada in 2013: Spathius agrili, Tetrastichus planipennisi, and Oobius