Hi Mats,

> 1. Does it work in practice?

Yes. Though labor intensive if used like Snelgrove designed it.

> 2. Is it sufficient to have the screen in for a week and then the swarming
> tendencies will be gone for the season?

No. It actually is used to make a two queen colony one above and below the
screen by spliting the colony and allowing the bees to make a queen above.
Then using the doors on the devise to milk the bees from the top down to the
lower.

> 3. Isn't there a risk that the bees above the screen feel queenless and
> start making queen cells?

Yes. Thats what you want. Thus the colony has completed the reproduction
cycle but they are still all in one hive then drawn off later ro the lower.

> 4. Any other tips on how to use it successfully?

Yes. Get the book called   Swarming: Its control and prevention by
Snelgrove. This method is thouroughly covered there.  Also check the
archives of Bee-l using snelgrove board as Mr. A. Morris has written a few
things on the subject if I remember correctly.

Clay