Noddy is correct, by the way. Their nest is somewhere in the lawn.
Gustavratzenhofer<geez, make this easier to spell why don't 'cha--LOL>
I think you are correct. If they are truly WASPS or HORNETS and not just what's known as 'sugar bees' or 'sugar wasps', you do need to find the nest in the ground and route them out. One located, it's a douse, and drenching of kerosene and burn to kill them all. If you are not familiar with how to do this, get someone who knows how. Do NOT try to do this yourself.
Please take care.