"Perhaps this would work or hornets?"   

That would certainly stop the hornets from entering the colony but it would not stop the drive by breakfast, lunch and dinner that radically thins out colony numbers.  When there are hornets about in number it also appears to affect the behaviour of the bees.  They are very defensive and less active based on our observations.

It has to be a one way trap but the design and lure are not known. 

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