Question
In the past two weeks, I have seen an insect on my silver maple that looks like a large (2 1/2 to 3 inches) wasp. It has a long tail 2 to 3 inches long, and is brownish yellow. I have noticed bore holes in a dead area of the tree trunk.

Answer
Sounds like a clearwing borer.  Clearwing borers are a group of day-flying moths with relatively scale-free wings. Many of these moths are similar in appearance to wasps, although they do not sting.

Which clearwing borer this is would be difficult without a picture of the insect. I would guess it is the maple callus borer. It does not really matter which one since the treatment is about the same for all clearwing borers.

Maple callus borer, Synanthedon acerni.
The larva of this clearwing moth is a borer in maple trees, especially around wounds. There is one generation each year. The moth has a wing spread of about an inch; both fore and rear wings are transparent with narrow purplish margins, tips of forewings are pale yellow, and there is a conspicuous black mark 2/3 of the way toward the tip of the front wing. Prevention of injury will be helpful in keeping the larvae out of the trees. Keeping trees vigorous and irrigated during prolonged drought helps to reduce borer injury. Onyx or Merit are an insecticides that will control this insect applied as a trunk spray can control the moths before they lay eggs and the larvae in the trunk. A more thorough control would be expected if treatments are timed to coincide with adult activity. Spray the trunk now and again in the spring to control the insects under the bark and in the spring to prevent further attack.

Here is a web link to information on clearwing borers if hardwood trees. http://www.entomology.umn.edu/cues/Web/088ClearwingBorers.pdf