I have a clump of white birch trees (4 trees in one clump) I noticed that one of the trees looks as if it has stopped blooming. The leaves are very, very tiny whereas the other three trees are healthy and have normal-sized leaves. Also, if I shake the trees, small bugs (look like little flies of somesort) will fall out, however the leaves on do not appear to be eaten or damaged. Is my tree dying? Or just a late bloomer? We are in Northern Wisconsin. Thanks!