In the 1950s, an introduced population of hemlock woolly adelgids (Adelges tsugae), native to Japan, was discovered on the East Coast of the United States. Since its introduction to the US, it has become a major destructive pest that is causing widespread mortality to hemlock trees. A member of the Adelgidae family, Adelges tsugae is closely related to aphids.
Another close relative of the aphids, Daktulosphaira vitifoliae, has also caused extensive damage as a destructive pest. The grape phylloxeran (D. vitifoliae), originally native to eastern North America, feeds on the roots of Vitis vinifera grapes, stunting the growth of or killing its vines.
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