hi everyone. i have another insect, or possibly disease question. last fall, or late summer i had gone to a townhouse complex and noticed lace bugs on a lot of the white birches over there. the whole place was infested. i sprayed for them and there were no more problems as far as i could tell. i went back there this spring to talk with the owner, and about 1/3 the tree had been defoliated. i have been driving around over the past months and have noticed the same thing happening with other white birches in the local area. they are partly or mostly defoliated. the lack of leaves is clear cut, not sparatic, but half a tree will be lacking leaves, or an individual leader will have the whole top bare. the problem is appearing in multiple towns, any thoughts from you guys as to what causes this? the trees i am seeing this problem in are about 20' tall. drop me a line if you have noticed this as well.