The most effective method for killing bees, hornets, wasps and yellowjackets is using an insecticide, according to the University of Minnesota Extension. However, the type of insecticide and how it is applied depends on the species of insect, due to the differences in their nesting habitats.
Generally, either insecticide sprays or dusts are used for killing stinging insects. Insecticide sprays are by far more common, as they allow a person to spray the nest from a safe distance. When used properly, these sprays are normally quite effective for killing visible nests of paper wasps, honey bees or baldfaced hornets, all of which typically nest above ground in out-of-the-way or hidden places.
However, if the nest isn't visible, it may be necessary to blow an insecticide dust into the area where the insects are seen entering and exiting. Insecticide dusts are usually more effective than sprays in these cases, as there is a greater chance for the insects to come into direct contact with the poison. These dusts are also the preferred method for dealing with yellowjackets, as they tend to nest in burrows underground. Still, sometimes yellowjacket nests can also be drowned by pouring soapy water directly down their holes.