Oak Galls

I found cocoon-like brown hard masses on the front side of a leaf.What are they???
Wed, Oct 8, 2008 at 6:13 PM
I was sweeping off the porch at the campground that I stayed at during the summer/fall.We had a big wind storm come thru and there were a bunch of leaves on the porch.On a lot of the leaves,I noticed these little hard brown cocoon-like circles on the front side of a leaf.I was thinking that cocoons were laid on the under part of the leaf,and that they were soft to touch,but these are hard and round.So I decided to cut one open and inside are these tiny red-orange color worm-like things inside.They moved a little bit,so I just thought that they were a worm of some kind.I’ve looked all over the internet and came up with nothing.Finally I posted my question and someone told me to contact you.I have pictures of the “cocoons” and the “worms” inside.The worms are very small and hard to see on the picture.Please help me identify w hat I’ve found!
Curious Nature Lover

Oak Leaf Galls
Oak Leaf Galls

Dear Curious,
Galls are growths on plants that may be caused by insects, mites, bacteria or fungus.  The Galls may occur on the leaves, stems, roots or flowers of the plants.  Most often, the Galls are plant specific.  We located a drawing in a very old copy of a text by Frank E. Lutz that we own.  The drawing is of a Oak Leaf Gall known as Dryophanta polita.  Since the text is a field guide, there was no additional information beyond the identification.  When we tried a web search of that name, be were led to several online texts that we could not access entirely.  One such text is Insects Affecting Park and Woodland Trees and the google teaser is “Oak leaf bullet gall Dryophanta polita Bass. A small, globular gall occurs in
numbers in August … ”  Another reference led to the common name Polished Oak Gall.  At this point, we can only speculate that Dryophanta polita is a Gall Wasp in the family Cynipidae, but curiously, it is not listed in BugGuide’s taxonomy for the family.  Another interesting side note is that Alfred Kinsey, most widely known for his studies of human sexuality and his best selling books in the 1950s, was first and foremost an entomologist who specialized in Gall Wasps.

Dissected Oak Leaf Galls
Dissected Oak Leaf Galls

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