Mats asked about swarm traps.

Effective swarm traps can come in many different shapes and sizes, but any beekeeper who has been around for awhile has had the experience of a swarm moving into an empty used hive body that was left near a bee yard.  It works just fine without frames or a bottom as long as it has a more or less rain proof top.  (Sometimes, not even that is needed.)   I think you would have best chances if you could find a way to put the box 2-3 meters up in a tree.  

If you at least as far north as Stockholm you should be able to put 1 or two drawn frames in the hive body through the prime swarm season without any serious damage by wax moth.  If you are in southern Sweden, I think I would try to set up the hive body without frames.

Recent US research shows that scout bees frequently choose a new home 2-4 weeks before the swarm leaves the hive.  Best if you have your "trap" set up no later than April 15.

Watch the box closely during swarm season (May and June).  You want to get any swarms out of the box as soon as possible so they don't get a chance to build lots of burr and brace combs.

You mentioned that you might want to catch some of your neighbors swarms.  There is some interesting law around concerning whether a beekeeper has the "right" to swarms from his hives...even on a neighbors property.  I don't know anything about Swedish law, but it may be worth checking.

Finally, be aware that you are not likely to cut down on the spread of Varroa by catching your neighbor's infested swarms.  It is believed that the primary way Varroa spreads is by "drifting" of bees...bees going back to a hive other than the one they came from.  In particular, drones have little attraction to their home hive and will go to pretty much any hive available.  The guard bees let them in, as they seem to know that drones will not start robbing.

Hope this helps,
Lloyd
email to [log in to unmask]
http://www.rossrounds.com
Lloyd Spear, Owner of Ross Rounds, Inc.
Manufacturer of round comb honey equipment and Sundance pollen traps