Fleas can begin with this case already - but not if the infestation extends over several rooms.

We had in our house really a huge flea infestation, the have us our cats that run outdoors brings.
In such an infestation of vermin, which extends not only to a room, this case is only partial fit.
If the Vieher are in one room, then this is certainly a good way to go without chemicals the bloodsuckers to the collar.
Finally, I can say: 5 fleas were in the case, but I do not want to know how many were in our house.
And the end of it was then - Fogger - 5 pieces distributed in the house, and that was that.