This is nothing but my personal opinion, but I can see several benefits to
having carpenter bees around.  It's fascinating to watch the males guard the
nesting sites, flying in place in the air like a hummingbird and driving off
other carpenter bees and even birds and people when they get too close.  They
are also good pollinators, I think, because of having long tongues so they can
forage from flowers with deeper throats than can honeybees.  They add spice to
life and make the world a more interesting place to live in.  They can cause a
few minor problems in homes at times, but you can take care of those, and I'm
sure they can find natural nesting sites in dead trees and other places.  But
if there were no more carpenter bees at all, we would all be the poorer for it
in my opinion.  I like seeing them around (especially in other people's yards.)
They are some of the best aerial acrobats I know of.
 
Layne Westover
College Station, Texas