native range aside from a short description of life-history traits and taxonomic descriptions, which resulted in focused research on its biology in North America. The insect was first identified in Canton, Michigan (near Detroit), in 2002, but it may have been in the U.S. since the late 1980s. It is suspected that it was introduced from overseas in shipping materials such as packing crates. Without factors that would normally suppress emerald ash borer populations in its native range (e.g., resistant trees, predators, and parasitoid wasps), populations can quickly rise to damaging levels. After initial infestation, all ash trees are expected to die in an area within 10 years without control measures. Every North American ash species has susceptibility to emerald ash borer, as North American species planted in China also have high mortality from infestations, but some Asian ash species are resistant, including F. baroniana, F. chinensis, F. floribunda, F. mandshurica, and F. platypoda. Green ash and black ash trees are preferred by emerald ash borer. White ash is also killed rapidly but usually only after all green and black ash trees are eliminated. Blue ash is known to exhibit a higher degree of resistance to emerald ash borer, which is believed to be caused by the high tannin content in the leaves making the foliage unpalatable to the insect. While most Asian ashes have evolved this defense, it is absent from American species other than blue ash. Researchers have examined populations of so-called "lingering ash", trees that survived ash borer attack with little or no damage, as a means of grafting or breeding new, resistant stock. Many of these lingering ashes were found to have unusual phenotypes that may result in increased resistance. Aside from their higher tannin content, Asian ashes also employ natural defenses to repel, trap, and kill emerald ash borer larvae. Although studies of American ashes have suggested that they are capable of mustering similar defensive mechanisms, the trees do not appear to recognize when they are under attack. Many of the specialized predators and parasitoids that suppressed emerald ash borer in Asia were not present in North America. Predators and parasitoids native to North America do not sufficiently suppress emerald ash borer, so populations continue to grow. Birds such as woodpeckers feed on emerald ash borer larva, although the adult beetles have not been used by any American fauna as food. Emerald ash borer populations