The grapevine is the only known host in the plant kingdom to the grape erineum mite, Colomerus vitis, sometimes called grape leaf blister mite. The mite is widely distributed, but usually causes only minor damage in commercial vineyards. The damage first appears as pinkish or reddish swellings or galls on the upper surfaces of the leaves. Beneath the gall, the concave portion of the leaf is lined with a felty mass of plant hairs or ‘erinea’. This is one of the most unsightly grape pest problems, yet it has negligible effects on vine performance. Control is usually by preventive applications of sulfur dust, and, as this is often applied to control powdery mildew, these mites are often incidentally controlled.