Though historically noted as one of the most noxious pests of vines in Europe, California, and other places where vinifera-type grapes are grown extensively, the grape phylloxera, Phylloxera vitifoliae (Fitch), was for many years of little concern to grape growers in Canada. In the Niagara Peninsula, where more than 98% of Ontario grapes, and more than 95% of Canadian wine grapes, are grown, the insect has been known for many years in its most conspicuous form, in galls on the leaves of wild grapes and a few unimportant cultivated varieties. The more infamous root form was known to be present, but the resistance of the older American varieties growing in most of the vineyards was regarded as sufficient protection from a native American pest that at one time threatened to destroy the French wine industry.