Appearance
The gall is rounded, sometimes elongate, and has a short, thin neck. Typically, galls are 2–3 millimetres in diameter, and may be numerous on the upper surfaces of leaves. They have an opening in the lower surface. At first they are yellowish-green or bright red, later they become dark red and black.In Britain, the mite affects introduced silver maple. The species is relatively new to Britain, being first recorded in London in 2002.
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