Just FYI, about 1 month ago, we saw 4 Asian hornets (large, orange death mask, orange feet) feasting on a dead bird in our garden. We needed to cut the grass, so we caught them under a big glass jar and transferred them elsewhere. My OH decided to spray them with Ajax while still under the jar and within about 5 minutes, they were stone dead.
I have no idea why Ajax would be so effective on them (perhaps someone chemistry/biology-wise could enlighten me?), but it was certainly more effective than any spray or other substance that we had tried before. I’ll definitely be wearing gloves the next time I use Ajax, though…
What with the increase in hornets in our area generally (Haute-Garonne) and the very unpleasant hordes of mosquitos this summer, we haven’t actually spent much time on our terrace this year. Short of cutting down all the trees and hedges in our garden, I don’t really know what we should do.
I didn’t know about the differences in numbers of queen hornets between the European and Asian species - thank you to Robert for that nugget.