Pete,
 
Without seeing the package that the flea powder came in I can't tell for
sure, but unless it's kitten-safe, it's probably too strong.  Flea collars
and flea dips are definately NOT recommended for ferrets.  Fleas can pose a
real danger to ferrets, so you'd be wise to try to clear up the problem as
soon as possible.
 
When you treat for fleas you have to treat the entire problem - ferret, other
pets, rugs, furniture, bedding, cages, etc.  Otherwise you're going to get a
reinfestation.
 
First use a kitten safe flea shampoo and follow the directions exactly.
Start by putting a ring of the flea shampoo around the neck to keep the
fleas from migrating up to the head as you wash the rest of the body.  Try
not to get it in its eyes but do a very thorough job.  Take all of the
bedding and wash it in hot water with bleach.  Take the cage and wash it with
soap and a diluted bleach solution.  Let it dry before putting the ferret
back in with clean dry bedding.  Wash out the litter pan with soap and bleach
too.  Remove the ferret from the area and spray the carpet and furniture with
a flea killer.  Make sure you've vaccummed before letting the ferret ren
around on the sprayed surfaces.  You might try adding some moth balls to the
vaccum cleaner bag to kill any eggs that might have been sucked up in it.
 
From the sounds of it I think I might try using some of those insect "4-Gone"
foggers that can do the entire house.  Follow directions.  go away with your
ferret for at least the recommended period of time.  Wipe off the surfaces
where the spray might have contaminated  before letting your ferret down
again.
 
Unfortunately you have to repeat the process once again in about a week to 10
days to kill off any that may have hatched from eggs.  After that, just keep
an eye out.  Once they get into populations like you're describing, it's very
difficult to control them.  It take a major all out war.
 
Dick B.
[Posted in FML issue 1200]