We had a yellow jacket plague here in Finland the year before last.
   and found the following seemed to help.
 
   1. Replace your open feeders with bucket feeders.
 
   2. If your using soft wood or fiber crown board, cover the edges
      with a hard material. I used carburetor tape I got from the
      local gas station. This prevents them from eating small
      entrance holes in the edges of the crown board and gaining
      access that way.
 
   3. Next place a 10 to 15 cm wide strip of plastic from the entrance
      into the hive, between the bottom board and hive box. I used
      the same plastic material my wife uses to wrap food with.
      Stateside I think it's called "Siran Wrap" or something like
      that.
 
      If you've noticed, when they attack the entrance, it's an
      organized attack with solders keeping the guards occupied while
      others sneek down the front of the hive box and over the bottem
      edge up into the hive. The plastic prevents this and gives the
      guards more time to react.
 
   4. Reduce the enterence space. The less space the guards have to
      cover the better. I reduced mine to approx. 10 cm. which seemed
      to work well.
 
 
 I hope the above will be of some help to you.
 
 Best regards
 
 Durk Ellison
 OH2ZAS
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