This is a swarm trap I made using a five gallon bucket. Five gallon is close to 20 liters so it may be smallish. I have had three out for about 6 weeks with no catch. Inside the top are five tongue depressors glued to a plywood roof 1 1/4 inch apart. Also a dab of lemon oil and a commercial queen attractant, again just a dab. The top edge is drilled with many 1/8 th inch holes, the bottom also, for venting. All are near commercial bee yards. No swarms, none, not a sniff. Do you think this is a bad design?