Question
I have a 6 year old oak tree.  It is approximately 6-7 inches in diameter at the base and 15-20 ft tall.  I just noticed a small hole on the south side of the tree which is about 2 feet above ground level.  I took a small wire and ran it in the hole to find that it went in and up toward the center of the tree (approx 45 degree curving angle).  The wire went in 5 inches before it hit a stopping point.

My question is -- what should I do about this?  My initial thought was to spray some insecticide in the hole and then seal it with some prunning tar.  Is this advisable or is there something else I should do in order to better diagnose the issue?  Other than this hole the tree appears to look very healthy.

Thanks for your advice.

Answer
Sounds like a borer--spraying an insecticide for borers into the hole will wok. One of the new insecticides is onyx. You may not be able to get that but check with your local nursery/garden type store for an insecticide for borers in trees. There is not need to put wound dressing on it since the wound will heal faster without the dressing.