Beth,
 
These bugs might not living in the poop.  (I don't know how close their
litter box is to their food) Maybe what has happened is the ferrets have
gotten some food wedged somewhere (in a corner, under a bowl) and it has
gotten wet.  This makes a perfect media for growing these little bugs,
which probably look a lot like fruit flies.  I hope you are able to find
the source of this and find some way to prevent if from happening, because
if this food or whatever has been sitting there long enough for bugs to
hatch in it it's probably rotten and stinky.  This happened to us once in
our Midwest cage when food got wedged between the bottom of the cage and
the plastic frame.  We had been noticing this really strong smell for about
2 days and washed what we thought was everything, hamocks, t-shirts,
super-cleaned the boxes, etc.  I finally noticed some of those little flies
and tracked them to the smell.  We took the plastic base down to a do it
yourself car wash and "power blasted" the gook out of there then scrubbed
it with the soap and brush.  It smelled SO bad.
 
We fixed the probem partly by moving the ferrets' food dish to another
place farther away from their water bottle and putting an t-shirt under the
water bottle and replacing it with a dry one if it gets wet.  We also
regularly vacuum the cage to prevent food from getting stuck places.  If it
is the litter box then I guess I'd just have to say change the litter box
more frequently until you get rid of the bug problem (also if you have any
fruit in the house check this for bugs too, it may be that you brought the
flies in on some food and they just decided the litter was a good place to
live too).
 
Leigh
[Posted in FML issue 2469]