Hello

This appears to be Zimmerman pine moth larvae damage. They tend to attack the tree in the trunk area where a branch emerges. While they prefer other species, they do attack white pines as well. To see a picture of a larva, be sure to scroll down and look at the “additional pictures”. These bulletins contain treatment information. If the branch is still alive there is no need to remove it. Treat the bark on the main trunk, which is where the larvae are, and treat at the appropriate time in spring.

https://hort.extension.wisc.edu/articles/zimmerman-pine-moth/

Pictures of where larvae are under a Pitch mass

https://extension.colostate.edu/resource/zimmerman-pine-moth/?utm_source=ExtensionBot

Try digging under a still soft fresh pitch mass to see if you find any larvae, and cn confirm Zimmerman pine moth. 

If tou see straight tows of holes long the trunk about 1/4” wide, then this would be from sapsucker or woodpecker damage. They drill multiple holes in fairly straight lines looking for insects. Pictures here - https://hyg.ipm.illinois.edu/article.php?id=247

For a second opinion, or to confirm why you are experiencing limb dieback, you may hire a certified arborist, one who has received training and passed certification testing by the International Society of Arboriculture. Find ones in your area by county or city search here - http://www.treesaregood.org