Hello All.
     I would like to add a brief note to this thread because it seems to
be a very significant one for the health of the bee colony.  Without
taking any accolades for personal habits, I want to point out that I
enjoy reading, especially regarding my pet creature, the honey bee.
Prior to developing double vision, I could be regarded as the proverbial
"book worm;" hence in many cases, I remember having read something, but
can't quite remember where. The case that comes to mind is one in which
I remember reading a research report relative to colony temperature
maintenance during the winter.  If I remember correctly, in essence the
author explained that honey bees utilized their intestinal contents as a
means of heat preservation during the winter (by merely keeping their in
intestinal contents metabolic byproducts).  From other readings, I
remember that "healthy" honey bees will never void inside their own
confines.  However, drones and "sick" bees will void within the confines
of their colony.  Agreeing with Frank, the presence of considerable bee
excrement within the confines of the hive, should be considered as  a
serious sign of illness of the colony and a good indication to check for
the cause of the illness.
Best regards.
Dr. Rodrigez
Virginia Beach, VA