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 BeeNet: 240:2358/100 email: [log in to unmask]