Scrape off as much of the tree sap as possible with a paint scraper. Be careful not to scratch the paint off the ceiling.
Soak a clean cloth in clear water, and hold it over the sap residue for 10 minutes until the sap is softened.
Dip an old toothbrush in water, and scrub it over the softened residue to remove it completely.
Dip the brush in white vinegar if the sap is still stuck on the ceiling.
Scrub the brush over the sap until it is gone.
Blot an adhesive remover on the sap stain if you can still see it.