@Linkat,
Oh and I have these ground hornets that come once a year - keep forgetting about trying to find something that stops them. I have found out they are not aggressive - they come for a couple of weeks - nest and then go off.
They just make a mess in our brick walkway. They like to nest in the soft sand that is between the bricks. Just makes a mess with these piles of sand that look like ant hills.
Some guy came by one year and tried to convince me they were dangerous so I should hire him to get rid of them. Thought better of it and looked it up and found they were not at all aggressive - which is good because before I knew they were actual hornets doing this - I was stepping on the hills to even them off - why I doubted him when he said they were aggressive.