John,
I've seen lots of live trees with sapsucker damage. I don't think drilling
will kill the trees. It may stress them, but holly seems pretty hardy.
Sapsuckers feed on phloem which they take out of the holes they drill
and the sap which accumulates there. They will also eat bugs which
are attracted to the sap. To some extent, they create their own food
resource. Does anyone know of other birds who do that?

Now, soap box time. I spend part of my time working on management of
natural areas. While holly trees provide a food resource for some
animals on those areas, they are invasive. Some woodlands close to
development in this area are getting pretty thick with holly. I don't see too
much fruit on those trees, but trees in lawns where competition is limited
are often covered with fruit. Every summer, I pull several hundred
seedlings out of my shrub beds, courtesy of my neighbor's trees. I
encourage anyone who can give up that beautiful holly in the front yard
to do so.

haven't come up with an invisible means of dealing with my neighbors
holly (or their cats) so this summer, I may practice my diplomatic skills. I
figure if I can handle those problems, I may qualify for a diplomatic job in
Bosnia or even get tapped for a rare bird committee.

Moving to Washington has given me a very different view of the holly
and the ivy.

John Fleckenstein
Natural Heritage Program
Washington Department of Natural Resources
John.Fleckenstein at wadnr.gov