Not to worry, this guy does suck on your tree but they rarely do any damage. It is a Spittlebug or Froghopper. Each of those globs is one insect, a nymph that manages to hide himself in...excrement by bubbling a viscous liquid. This is great protection from predators and the elements.
Easy to control, just spray with a hard stream of water. Your tree should be fine unless they are in huge numbers and you can't spray high enough. I've never seen an infestation of these guys like that but if they are maybe a call to a tree company (they have the insurance to deal with trees and heights). The strongest pesticide I'd allow would be soapy water or neem and make sure they have their current pesticide applicator license!
Otherwise, no big deal! Good news, huh!