Hoverflies closely resemble wasps and small bees. Evolution has provided them with this camouflage because it causes apprehension and fear in potential predators. The fake warning signal is known as aposematic colouration. Hoverflies have two natural predators that will hunt and kill them, but the most effective way to rid yourself of these pests is to destroy the food source. First, you must determine that they are, in fact, hoverflies.
Identify the hoverflies by determining the number of wings. Hoverflies have two wings; wasps and bees have four.
Introduce solitary and hoverfly parasitoid wasps into the area. The best choice is the ectemnius cavifrons, a wasp that specialises in killing hoverflies.
Starve hoverflies by removing the source of food. Remove all flowers and other pollen and nectar-bearing plants from the area because hoverflies eat and digest pollen.
Kill individual flies you encounter with the flyswatter to further reduce their numbers.
Parasitic and solitary wasps are not common wasps. They are rare and need to be purchased at specialised online gardening stores.