What is this?
This is most likely a type of gall formed on a tree in the area. If you can find out what type of trees are in the area the gall was found,
we may be able to narrow it down. Also, cut one of the galls in half and attach a picture of the inside. (Some galls have some liquid inside, so protect your work
surface and your hands-- some galls were used to make ink in the past.)
You may want to investigate further by using a pair of binoculars and looking up at the trees branches. These galls form on leaves, twigs, and sometimes on the fruit
of the tree; then they fall to the ground. The brown gall was probably green or yellow or reddish, while on the tree.
The picture looks like an Oak Apple gall or Acorn Plum gall. There are at least 50 different insects that form apple-like galls on Oaks. Some are
hollow inside, and some have a spongey or fibrous interior.
Here is a link with some pictures:
As the linked article states, galls are not a concern; they rarely affect the health of the tree.
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Thank you for the information. The trees growing in the area are, Oak, White ash, Maple and a few Birch. I am attaching a picture of the inside.
Thanks for the great picture of the insides. This is an Oak acorn plum gall. The insect that causes the gall is listed as Amphibolips prunus in some scientific references.
Other references may list another species of Amphibolips. Depends on the exact type of Oak from which the gall fell. At the very center of the gall is
a tiny single larva of the wasp. Here are a couple links to more info on the gall and insect. They are not harmful to the oak tree.
(scroll down in this article to the section on "Acorn Plum Galls"
Here is a nice 'bug' site with pictures=
Here is an amusing article on the gall with some nice pictures:
So, you can enjoy the galls and no harm will come to your trees.