What is the glue on pine trees?

The glue in pine trees is sap. This sap has been made into glue by native Indians for centuries.

To make pine sap glue as the Indians and pioneers did, melt the pine sap in a small can or tin over a campfire. Leave room in the tin for some crushed charcoal (make this from the remains of yesterdays campfire) Mix crushed charcoal into about 3 times as much hot pine sap and you now have glue that will stick many things.) Even though the remains will harden, each time you melt them you will have usable glue again. -Good camping.