Sand wasps are meddlesome insects that burrow underground in sandy places like patios, sandboxes, and gardens. They are considered solitary wasps, though it's common to find many females living in the same area. They create tunnels in which to lay their eggs and provision their nest with paralysed flies. These insects usually appear in spring and remain throughout the summer and early fall. Removing sand wasps is a relatively easy process, though you should take all the necessary precautions to avoid being stung.
Determine that the species you are dealing with is in fact the sand wasp. This is a solitary species that lay single eggs in the sand, close the nest and move on. They are relatively harmless, as opposed to social wasps like yellow jackets that swarm and aggressively protect the nest. If you discover a yellow jacket nest, contact a professional to remove it as they can be quite dangerous.
Cover the patio or sandbox with an indoor outdoor carpet. Wait until after sunset to do this, as the wasps will be less active. Make sure to cover all of the nesting holes. Secure the carpet with some kind of weight.
Wait about a week for the sand wasps to find a new home. They should relocate without any further actions. By doing so you have removed the wasps without killing them.
To prevent wasps from returning to your patio, fill in the cracks where they built their nests with a silicone caulk.
If the wasps continue to be a problem, try an insecticide dust such as Sevin Dust which commonly used on tomato plants. Sprinkling this dust in the nesting holes of the wasps will kill them.
To prevent stings, avoid wearing scented perfumes or any sweet-smelling cosmetics when approaching the wasps. Avoid wearing bright clothing and always wear proper footwear. Food, beverages and trashcans attract all kinds of wasps and bees. Don't remove wasps unless they are really posing a threat. Wasps provide excellent pest control for your home and garden.
Do not deal with wasps directly if you have any kind of allergies to stings.