Today I learned that the mud dauber wasp nest over my back door contains no actual mud dauber wasps, that even if there were one around, you'd have to try to pick it up to get it to sting you, and that the best way to control them is to remove the spider webs that attract them. They sting spiders and other bugs and leave their bodies inside the nest for their larvae when they hatch. Once the holes appear that show the larvae have grown up and left the nest, all you have to do is hose the mud off
@AlphaCentauri I have been stung multiple times attempting to remove mud dauber wasp nests.
Some mud dauber wasps, apparently, do indeed guard their nests.
I promise I never tried to pick a wasp up. They hate that, and it would be rude.
It is true that they are not very aggressive most of the time, though.
@AlphaCentauri Yes, they are totally benign and will only sting non-spiders in self-defense. They are one of the good guys.