Fly parasites are very small, harmless insects that nature has programmed to
attack and kill flies in their immature pupa stage. The fly parasites attack most species of
flies normally present in animal manure and garbage.
The fly parasite is effective because it kills the fly before it reaches its adult stage.
Because of the flies natural advantage (produces more eggs, has a shorter life cycle and
travels distances) it is best to release small amounts of parasites throughout the fly season
instead of one large release. We recommend releasing flies every two weeks for a
minimum of 10 weeks in most areas.
Up on arrival, the fly parasites will be close to hatching from the fly pupae. Once
hatched, they will immediately search for fresh fly pupae in which to lay eggs. The
female fly parasite lays up to 50 eggs during her life. She will live two to three weeks
depending on the climatic conditions. The parasite egg is laid inside the fly pupa and the
fly parasite larva will hatch and consume the developing fly pupate, then hatch out into
an adult parasite.
The fly parasites are shipped, still developing inside the host, packed in a paper
bag mixed with wood shavings for protection. Depending on temperature conditions
during shipment, parasites will start hatching 2 to 5 days after arrival at 80 degrees F.
Warmer temperatures will make them hatch sooner, while cooler temperatures (60-70F)
will slow them down. DO NOT FREEZE THEM. Upon arrival, the fly parasites should
be kept at 78-85 degrees to promote hatching. DO NOT leave them in direct sunlight or
The best time to start releasing is when some parasites have hatched in the bag.
Keep the closed bag in a warm place out of the sun until you notice some parasites
walking around inside. The best place to release the parasites are as close as possible to
the breeding sites where fly larvae activity can be seen or is expected.
It is best not to release all of the parasites in one spot. Try to cover the entire flybreeding
area. Fly parasites will move around in a 100 yard radius in search of fly pupae
and will even burrow into the breeding site. Simply sprinkle them out of the bag and
throw them by hand onto the breeding site. If direct sunlight is a problem, covering the
pupae with dirt or organic matter is advised.
Use of commercially available fly baits and or traps could help considerably in
controlling the migrating adult fly population. Be careful, spraying chemicals to kill
adult flies close to release sites may result in killing the parasites too. Use sprays on
structures where flies are resting. Flies quickly develop chemical resistance, so be