These wasps find a prey and sting it, which paralyses the victim. In this case, it is a spider, but I have seen wasps drag big caterpillars and grasshoppers that were much bigger than they were.
The victim stays alive but, being completely paralysed, cannot move.
The wasp then leaves it and go dig a hole. They are quite proficient diggers, you can see the sand flying when they get into it. Once they have dug a hole, they go back to get the paralysed insect and drag it to the hole they have just dug.
|Wasp dragging the spider it has paralysed|
It then lays its eggs on the victim, so that when they hatch, they have access to fresh food. I have never actually seen the wasps lay the eggs.
When they come back, after digging their hole, to get their prey, they seem to have only a general idea of where they left it. They start looking around in an area of about a square meter. It is the same with the hole they dug up. When they return with the victim, they seem not to know exactly where the hole is. Usually they are not far from it, but they have to put down the paralysed insect and look around for the hole, which sometimes takes them several minutes.