If you are seeing wasp-like insects hovering over a lawn area, they may be Solitary Wasps.  These wasps are hunters, looking for insect prey.  There are different species of Solitary Wasps, but all of them are hunting other insects.  Some are looking for spiders,  grasshoppers and crickets.  Still others, will hunt ants, flies, bees, butterflies and moths.  Most Solitary Wasps are not harmful to people, and will in fact, fly away to avoid human contact when approached.

When a Solitary Wasp catches it’s prey, it paralyzes it, and carries it back to its nest, which many species will have in ground burrows.  After carrying them into their nest, they lay eggs on them.  The prey will live until the larvae emerge to eat the prey.   Most species never see their parents, since  they move on after giving their offspring all they will need to survive.