Answer: What you describe sounds like maple bladder gall or spindle gall. These galls are caused by a small mite, Vasates quadripedes (Shimer). The structures are generally noticed first in May, about the time the leaves have become fully expanded. At first the galls are green but they quickly turn pink to red and eventually black. Leaves frequently become so covered with the galls that they completely twist out of shape and may even drop early. Removing the leaves won't hurt your trees. In fact, the leaves would have fallen off eventually on their own. Some years are worse than others in terms of leaf damage. The little pests are difficult to control. Since these leaf galls do not cause any real harm to the trees, control measures are not generally needed. Glad we are able to help answer your questions. Feel free to stop in again!
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