I don't put flea collars on my pets anymore because there are better
and safer products to use on them, but I have a new reason to buy the
collars.  We have had wasps nesting under our deck for years.  The
deck is so low that we couldn't climb under it to spray wasp killer or
do anything else.  This year I started seeing wasps at the deck as
soon as it warmed up enough for them to fly.  I bought two flea
collars and slid them between the boards near the places the wasps
would frequently walk through the cracks, with the clasp still topside
so the collar dangles.   We don't have wasps under the deck anymore.

Since the clasp for each collar is still on top just spanning the
crack in the floor boards, I can pull it up and dispose of it at the
end of the season.  Hopefully I won't need to buy any next year, but
at least I know it works.  I thought there might be others here who
could use the this tip.  
Debra in VA
See my quilts at
http://community.webshots.com/user/debplayshere