Digger bees is a common name often applied to insects including bumblebees, ground bees, cicada killers wasps, yellow jackets and digger wasps. All build nests in abandoned burrows or by digging out soil. However, some kinds are far more aggressive than others. According to GardensAlive.com, insects that are two inches (5 cm) or longer are probably cicada wasps that have no interest in stinging humans. Flying insects that are under an inch (2.5 cm) in length and feature yellow stripes should be regarded cautiously; they are most likely highly aggressive yellow jackets. Bumblebees are also known to aggressively defend their nests if threatened.
Fill a wheelbarrow with ice shavings, chips or cubes.
Cautiously approach the site of a nest---marked by an entrance/exit hole---and dump the gathered ice into the hole. Cover the rest of the area around the hole with ice.
Cover the entire area with a tarp.
Weigh down the edges of the tarp with wood planks to create a seal and deter any insects from escaping.
Fill in the hole with dirt or debris after the ice has melted.
Bug zappers are also effective. Simply place one or more zappers near the entrance of a ground nest and turn it on. If the insects are aggressive yellow jackets or bumblebees, they'll fly out to defend their nests and get zapped.
Approach a ground nest only on cool evenings. Colder temperatures make it harder for the wasps or bees to fly, and covering the nest site at night ensures that the majority of insects are inside.