The maple bladdergall mite (Vasates quadripedes) and maple spindlegall mite (V. aceris-crumena) are found throughout the range of sugar maple. The former is characterized by a globular gall that is 0.05 to 0.1 inch (1 to 3 mm) in diameter. The latter induces an erect, elongate gall approximately 0.2 inch (5 mm) long (Fig. 68). Both of these pouch-like galls are found on the top of the leaf and usually are limited to understory leaves. When first formed (in May), the galls are yellowish-green. They turn rosy pink and eventually may become dark red.

The crimson erineum gall mite (Aceria regulus) is responsible for the bright red pile or felt-like patches (erinosis) on the upper surface of maple leaves (Fig.69). A related species causes a similarly shaped but whitish to green erinosis on the underside of sugar maple leaves.