This Digger Wasp, which I think is probably Podalonia tydei in the Sphecidae family, has just stored a caterpillar in a burrow in the sand and closed up the entrance.
The wasp paralysed the caterpillar with its sting before carrying it back to the burrow and then laid an egg on top of it before sealing the entrance.
Before long the egg will hatch and the new born bub will spend the rest of its larval stage eating its mattress before pupating and emerging from the ground as an adult wasp.
The mother wasp here has just spent several minutes carefully sealing the burrow entrance and landscaping the area to show no sign of any wasp activity at all. There are, after all, unscrupulous creatures out there, including other wasps, that would happily parasitize her captive caterpillar with their own eggs after she's done all the work, and even parasitize her baby - the cads!