Fly Parasites

The Problem

A high density of any livestock or poultry animals brings a huge amount of filth flies (stable flies, etc.). These flies can reduce production if there are too many of them. A total elimination is impossible due to their speed of reproduction: a fly lives an average 30 days and can lay up to 900 eggs. Use of chemical insecticides is costly and not so efficient. Flies can quickly develop pesticide resistance, and there is growing concern from both producers and consumers of chemical residues in animal products and negative side effects to the environment.


Fly parasites are Hymenoptera (wasps) from the Pteromalidae family. These tiny wasps (about the size of a flea) are the main natural enemies of filth flies. They are specialized in searching for fly pupae, and subsequently parasitizing them. They are very specific in their host, and pose no harm or danger for humans and livestock. Also of importance is the fact that there is no build up of pesticide residues, and resistance issues associated with use of pesticides are eliminated.

Safe for human and animal health, fly parasites provide a good biological solution for a cost effective reduction of fly populations.


Flies are attracted by various types of organic debris, especially fecal matters, broken egg shells, and animal food. A female can live for 30 days and lay up to 900 eggs in her adult life. Eggs are laid in masses in manure. Larvae (maggots) develop in decaying organic matter and migrate to dryer places to begin pupa formation. From pupae emerge adults ready to lay eggs again. It takes only 7 to 10 days during warm temperatures to develop a fly from egg to adult.


Female parasites are highly specialized in searching for fly pupae hidden in organic matter. When a female parasite finds a pupa she pierces a hole in the pupal casing with her ovipositor (specialized egg laying device) and injects an egg into it. The egg hatches quickly into a larva and begins feeding itself on the contents fly pupa. As the fly parasite goes through its own development, it eventually causes the death of the fly before it has a chance to reach its adult stage. Eventually, a fly parasite instead of a fly emerges from the pupal case. A large portion of the fly population is thus destroyed by the first application of the parasites. However, flies have many inherent reproductive advantages over the fly parasites, and therefore regular introductions of parasites will be necessary to keep the fly population under a tolerable level.

Using fly parasites is the Biological part of an Integrated Pest Management (IPM) system. IPM is using all the control measures available to control the pest. Other components of IPM are Cultural, Mechanical, and Chemical. More information on how to implement IPM techniques to minimize your pest populations can be attained by contacting Bugs For Bugs.


  • Cows/calves/cattle
  • Pigs
  • Poultry
  • Horses


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