There are 3 species of predatory fly parasites mixed in your order: Spalangia cameroni, Muscidifurax zaraptor and Muscidifurax raptorellus.
Fly parasites search fly-breeding areas for fly pupae containing developing flies. Once inside, the eggs hatch inside the fly pupa and feed on the developing fly and after two to three weeks of feeding, an adult fly parasite emerges to repeat the cycle. Each female fly parasite can kill approximately 100 immature flies in her lifetime.
KILLS MOSQUITOES BEFORE THEY BECOME OLD ENOUGH TO BITE
Kills mosquitoes for 30 days or longer when placed in standing water outdoors. Can be used in bird baths, rain barrels, old automobile tires, ponds, ditches, unused swimming pools, tree holes, flower pots, roof gutters or wherever water accumulates.