Isn't that an awesome name? Great Golden Digger Wasp. For once, the common name is much more evocative than the scientific name, which is a mundane Sphex ichneumoneus. That sounds almost...base, icky, ignoble even.
Yesterday, while I was weeding, I noticed one individual continually buzzing around nearby, focusing on a little patch of dirt in a small corner of the front garden. Watching for a few minutes, I finally saw her enter a hole in the ground, then come out and fly off a minute or two later.
There is one generation each year. One generation annually is typical for predatory species. Plant eaters, on the other hand, reproduce like rabbits. Seriously... since rabbits are plant eaters. In fact, insect plant eaters will reproduce much more rapidly than rabbits. That's why predatory insects are so important: to keep herbivorous insects under control. This dynamic is one of the main reasons why spraying insecticides, which kill off both herbivorous and predatory insects, will almost always result in herbivorous insect populations rebounding crazily, meaning that you soon have a worse problem than you started out with. You've killed off the insect predators, and they may take years to rebuild their populations to pre-spray levels.
Great golden digger wasps, like solitary bees and wasps in general, are calm and gentle. They generally will not sting unless you try to actually handle them, but if that occurs, their sting is often extremely potent and painful. Just leave them alone and enjoy watching them go about their business. You'll be glad you did.