We plan(ed?) to dig out the planter to day.  The goal is to seal it from the top with screen, to discover if the black bugs are coming out from the top.  We are trying to eliminate one variable at a time until we get rid of the bugs.  There is also the possibility that:

• the bugs are flying into the house by coming up the pipes that drain into the planter. 
• for an unknown reason water from outside is flooding into our green house via ground seepage.
• the bugs are living on the water than condenses under the granite slabs covering the planter.
• the pipe that drains into the planter is too low, and so the planter overflows around that juncture.

It is raining today, though, so we may not actually get passed the possibilities and into any work today.