> hawking up and down in front of the hive rather than trying to enter it

Yes, this is one scenario, but there are many videos showing that the hornets will land on the hive (or landing board, if any) and grab bees coming out of the entrance, so the Thorne mesh certainly stops the hornets from landing and blocking the entrance, and may allow bees to disperse as they take off, and divert them from the predictable, slow straight-line sortie take-off, which the hornets exploit.

Thorne does not sell junk or useless gadgets.  I have sold Bee-Quick to Gill and Paul Smith (Gill is a Thorne daughter) for decades, and they clearly refuse to put substandard items in their catalog, so someone must have tested this approach/device, and found it to be beneficial.  

That said, while it will require regular maintenance, sticky cards seem to work very well, as a trapped hornet will attract others with a pheromone.  So, catch one hornet using the sticky card as a net, and it will attract and kill more hornets.

https://youtu.be/BImReJPOgB8
https://youtu.be/Oc28b6YE4jE
https://www.reddit.com/r/Beekeeping/comments/164i7r0/asian_hornet_attack_on_my_hive/

The closest I have ever come to this kind of problem was a mockingbird that learned to swoop across the entrance to hives, and catch returning bees on final approach for landing, so I rigged up some plastic bird netting between bamboo poles on each side on the cluster of hives at issue, and this discouraged that very smart bird.

If hornets ever do come to my area, I foresee a new form of trap and skeet shooting - an alternative to sporting clays, one that any beekeeper can enjoy without any concern as to registration, regulations, or noise complaints.

But, one will need some Co2 to get enough muzzle velocity to kill a hard-exoskeleton beastie: 
https://www.bugasalt.com/pages/shop-collections#shreder

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