http://tinyurl.com/3ekld

Please click above and tell me what kind of tree this is, and if the
lichen that seems to be taking over the bark of this tree is killing
it. It's been a slow year for trees this spring, so I am not sure if
the tree is dying or not. I did prune quite a few dead branches,
however.

The bark is crawling with aphids too. Does this mean anything?

Thanks!