Thank you so much for this informative article--I've seen these critters, and thought they were scarier than they actually are! Now that I know they are beneficial, I'll be glad they have come to live in my garden.
They're probably one of the most misunderstood insects that a gardener will run across. There are several species of Digger Wasps that you should be aware of. The Black Caterpillar Hunter does hunt caterpillars, and others, such as the Thread Waisted Wasps will hunt various beetles and crickets. I find them fascinating, and encourage all of them at my flowers.
Wasps are actually my greatest fear. Some hate snakes, roaches, mice... not me. I can't stand wasps. They send chills through me and make my hair stand up. I really appreciate learning about these mostly harmless wasps with such entertaining habits. Makes them slightly less intimidating.