Hi,

We have a small River Birch (around 7' tall) that was growing vigorously.
Lately we have noticed some of the leaves are a lighter green than the
others. Additionally, these leaves have a "wrinkled" appearance. When we
water the tree, lots of what appear to be wasps fly off of it. Is there a
wasp that attacks the leaves on this tree or do we have another as yet
unseen pest? What would the group recomend to control this outbreak?

This is one of our favorite trees and apparently a favorite of insects as
last year we battled the Japanese beetles for it.

Thanks in advance for any help.