Before you swat that tiny wasp away, take a closer look.
It may be one of the Good Guys.
Like other ichneumon wasps, Exochus females insert their eggs into the larval stage of many leaf rolling caterpillars, such as the orange tortrix and the obliquebanded leafroller. The eggs then hatch inside the caterpillar and begin feeding. You can see video of an Exochus female attacking a caterpillar here. The video is bit long, but fascinating.
These tiny wasps serve us well in the garden, so avoid using any broad spectrum pesticides and let nature take its course.
You can grow a surprising amount of food in your own yard. Ask me how!