[savedbygrace]

Are they Carpenter Bees?

http://ohioline.osu.edu/hyg-fact/2000/2074.html

Look for 1/2 inch to 3/4 inch round holes in the exterior woodwork on your house. The males who ‘patrol’ the area cannot sting, but the females who stay in the nest can sting when aggravated.

[fireforeffect]

Fairly easy solution to Carpenter Bees.

Checkout the pesticide section of your hardware store. Look for termite and carpenter ant killer (contains bifenthrin). It also prevents/kills carpenter bees.