What's in this cocoon?

[millstreaminn]

Was out trimming the lower branches off my pin oak trees and saw quite a few of these little pea shaped cocoons. They've got a tiny breathing hole drilled in them, are hollow and the bug inside is green and about 1/4 the size of a grain or rice. I googled pin oak, pests and pea sized cocoons, but can't find anything that looks like what I have. Just wondering what little critter is gonna hatch and attack my threes this time...

 

[CottageFarm]

could be this....

http://www.ces.ncsu.edu/depts/ent/notes ... ote05.html

 

[cowgirl8]

I believe thats a gall from wasp...they dont hurt anything

 

[Workinonit Farm]

could be this....

http://www.ces.ncsu.edu/depts/ent/notes ... ote05.html

Great link!!!

Thanks for sharing.

Katherine

 

[Hook]

It's a gall.