Insects on Leaf - Ask Extension
I have noticed red insects (?) on many of the leaves of a tree in my yard. Some of the leaves of this tree are stunted compared to two similar trees i...
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Insects on Leaf #930762
Asked May 05, 2026, 9:03 PM EDT
I have noticed red insects (?) on many of the leaves of a tree in my yard. Some of the leaves of this tree are stunted compared to two similar trees in my yard that do not have the insects..
Montgomery County Maryland
Expert Response
Hi Peter,
Those red objects are bladder galls, which are fairly common on maples. They're caused by an eriophyid mite feeding within the gall. Galls do no real harm to the trees and by the time you see them, it is too late for treatment. Maple bladdergall mites will not infest any other plant except maples.
You mentioned some of the maple leaves are stunted. Since you only provided the one picture of normal leaves with the galls, I'm not sure what would cause stunting. You may want to have your tree evaluated by a certified arborist to determine the cause, but it is not due to the galls.
Marie
