Acorn Plum Wasp Gall – Identification

Q: Found this under a red oak. It “bled” when cut open, but it’s now dried up to a woody lump.

A: It’s an acorn plum wasp gall. It forms beside acorns as opposed to the spongy oak apple gall, which forms on leaves.

Acorn Plum Wasp Gall

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