When the wasps have nested, you can dust using the insecticide as explained by this website. You will be required to identify the species of the wasps because the insecticides that are used differ depending on the species. You ed to ensure that you spray while you are far away thus the need to consider your skin. After you have sprayed, you can cover the nest and spray any wasp that is coming out. You can bring down the nest after you are convinced that they are all dead and destroy the nest. Through this you will learn that it is the best way to ensure that no other wasps will be attracted to the area.