Hello all,
I have a 14 foot swamp white oak that is covered
with galls. Flying and landing on the galls are hundreds
of different kinds of wasps. They seem to be landing
only on the galls but not doing anything to them. Inside
are larva of another insect but the wasps do not seem
to be biting their way into them. There are no holes anywhere.
Why are there so many wasps congregating in this tree?

check this out:
http://entomology.unl.edu/ornamental.../gallwasps.htm