something on his ear

[corellian_ninja]

My gelding has something really sticky on the tip of his ear. I suspect its tree sap. I left it alone for a few days thinking it would just.. come off, but it hasn't. It doesn't seem to be bothering him at all, but its bothering me. It won't flake off, didn't soak off with a wet rag, and I'm afraid picking at it will hurt his ear. 
Can you guys recommend something that might loosen it safely?