>I realize that diazinon is a dangerous pesticide to use around beehives, but
>sometimes there seems to be no alternative.  In southern Michigan, we have a
>medium sized ant species (black and brown) that builds large hills....
 
I have also resorted to using diazinon in desperation in my overwintering
areas as an ant control.  These areas are ant heaven due to large amounts of
dead bees in the spring, occasional sugar syrup spills, and they are cut
right into the southern edge of thick coniferous forest.  I usually wait
until I have moved the majority of the hives out.  We have a very small red
ant here that lives in sandy soil and does not seem to have a concentrated
nest site.  That is, there are numerous small entrances in the ground all
through the whole area.  Fortuneately this ant is not a deadly pest.  It can
enter the hive through very small cracks, but its only interest seems to be
in seeking sweets.  The carpenter ants will go right into the bottom boards
and supers of any hive that is weak.  In Kenya I noticed that all the hives
are suspended with greased ropes as ant/termite control.   I used to have
some hive stands on legs that I put in cans of oil.  But once I started
keeping larger numbers and moving them this was impractical.
I wish someone would suggest some alternatives.
 
I can suggest one fairly mild ant killer, but in my experience it is only
useful against smaller ant colonies.  I use it in blueberry fields (which
are acidic and often highly ant infested).  If you buy a box of powdered
borax laundry powder (this is about 99% pure borax in the popular brand) you
can mix it into a heavy sugar syrup but do not exceed 5% or the ants might
not take the bait back into their nest.  I usually place the bait under old
boards, but I have often worried that the bees might find some.  Could
anyone comment on the toxicity of borax to honeybees.