Vacuum cleaners kill fleas just as well as any poison
   a standard vacuum cleaner abuses the fleas so much it kills 96
percent of adult fleas and 100 percent of younger fleas.
  So no need to worry that a vacuum cleaner bag may turn into a fleabag
  the vacuum brushes wear away a waxy outer layer on insects called the
cuticle. Without it, the fleas, larvae and pupae  dry up and die
  Researchers have ran their experiment
several times.
  "We didn't do a post-mortem, so we don't know for sure. But it appears that
the physical abuse they took caused them to perish
  Fleas spread diseases such as plague and can transmit worms.
  "There are all kinds of ways to manage the problem, but how people feel about
insecticides and how much money they want to spend factors into what they're
going to do for flea control. Vacuuming is a great strategy because it involves
no chemicals and physically removes the problem