Greetings Joe:
From your description, it appears you may have pine spittlebugs. If the infestation is light, use of a garden hose with a directed stream of water may prove quite effective. However, if the infestation of spittlebugs is heavy on your white pine, you may wish to use an insecticide such as malathion or sevin during mid-July.
Remember to read and follow pesticide label and instructions.