5,000 Fly Exterminators – Bulk Breathable Bag


Approx. 5,000 Fly Exterminators
Packed in retail breathable pouch.
(Case count N/A for bulk qtys.)
UPC Code:N/A

Fly Exterminators are small wasps that are used to control flies in animal manure accumulations/compost piles and other similar types of breeding sites. These insects parasitize numerous types of flies, infecting the flies in their pupae stage. These tiny insects are stingless, biteless, and harmless to humans and animals.


About Fly Exterminators

Fly Exterminators are small wasps that are used to control flies in animal manure accumulations/compost piles and other similar types of breeding sites. These insects parasitize numerous types of flies, infecting the flies in their pupae stage. These tiny insects are stingless, biteless, and harmless to humans and animals. The Fly Exterminators are shipped in wood shavings as pupae (cocoons) and should be used monthly during peak fly season after pupae hatch. All units include complete release instructions and storage instructions.

Preys On: Houseflies, Biting Stable Flies, Garbage Flies, as well as minor control of several other species of flies.


Release Instructions

For Fly Parasite Program:

• Start program at the first sign of flies and keep up with regular releases until fall and plan for weekly average of 800-1000 parasites per large animal, 300 for small animal or 1 parasite per 2 birds during fly season.

• The number of parasites can start low and then increase with warm wet or humid weather.

• During manure clean-out, save the top few inches of organic matter which contain breeding parasites.

• Trap adult flies to reduce the quantities of parasites needed for release.

For Release:

• Shipped developing inside of fly pupae; some adults are emerging at time of delivery.

• Wasps do not bite, sting, swarm, infect or otherwise bother humans or animals, they only attack fly pupae. Parasitic wasps usually search at night and burrow under surface of organic matter.

• Keep at room temperature of up to 90°F with good air circulation. Keep out of direct sun.

• Use this within 48 hours of receiving.

• Apply where flies lay eggs and pupate sprinkle as widely as possible on or in organic matter.

Release Rates 

*Release rate guideline are for preventative control. Heavier infestations may require additional treatment.


These small parasitic wasps are the most natural enemy of flies during the pupa stage. We provide several species of the tiny wasps in the general Muscidifurax and Spalangia that attack and have adapted to different climates with a higher proportion of Spalangia in proportion to Muscidifurax. The eggs of the parasitic wasps are laid inside the fly’s pupae and the developing flies provide food from within for the young wasps.

Fly Parasites control flies in animal manure accumulations and other filth fly breeding sites. Very effective against the housefly, biting stable flies, garbage flies, and the lesser housefly which make up to 95% of the flies in manure and other site accumulations. Five percent of the other flies are also parasitized, such as false stable flies, face flies, flesh flies and horn flies, but control is less complete on those flies since these flies complete their life cycle widely dispersed in the pasture.
Fly Parasites do not bite, sting, swarm or bother anything else, humans, or animals included. Fly Parasites are nocturnal and are rarely seen during the day. They operate to a depth of 8 inches in the manure, homing in with their biological radar on fly larvae that are about to pupate.

Fly Parasites arrive in wood shavings in the immature stage, inside a pupa (cocoon), which looks like a black rice kernel. When fully grown they will cut a hole in the pupae case and exit as adults searching for more fly larvae, seeking to lay their eggs where the flies pupate.

A few days after arrival the Fly Parasites will begin to emerge from their cocoons, which is when you should sprinkle them on or near fresh manure and other pest fly breeding areas. To release, nothing could be easier, you just sprinkle Fly Parasites out of their shipping pouch near manure area and then lightly cover to protect from birds. Fly Parasites will self-distribute up to 100 yards but will not fly or crawl on or otherwise bother you. In early Spring Fly Parasites should be released at the first sign of emerging or immigrating pest fly adults to minimize the number of adult flies that are laying eggs. Very early releases can be smaller in number, increasing the quantity at the first sign of active breeding. Be sure to be proactive and not reactive, monitoring the piles of manure around your animals and their living quarters.

Top priority release sites are barns, stables, and kennels, in and around coops, stalls, with special attention to hospital and calf pens on dairies and horse stalls, on feedlots and wherever straw bedding is provided for animals. Having other fly-breeding areas near (but never directly in) water sources, and decomposing matter, garbage cans and septic tanks. The widest possible dispersal of the parasites is best.

Once the parasites are established fewer parasites may over-winter outdoors, yearly releases are necessary in order to prevent a build-up of flies.

Preventive measures to prevent fly buildup are a much easier strategy than getting rid of them. It is imperative to keep the number of adult flies down.

Bait Trapping: It is both economical and safe to use bait traps to kill large numbers of adult flies without interfering with biological controls. During the first few weeks of summer it is important to lower the adult fly density before seasonal hot weather arrives. In areas with humid weather and wet manure accumulations, both releases of parasites and bait stations are needed to give excellent fly management. The number of traps should be increased along with parasite releases until the adult flies are gone.

Managing Manure: It is imperative to practice good sanitation, which will then eliminate the conditions favorable to fly breeding. Remove manure frequently, leaving a little of the top layer of manure in place in order to leave some of the complete complex of beneficials to keep destroying flies. Keep manure dry and eliminate wet areas where possible while maintaining ventilation. Clean up feed spills where possible. Use hydrated lime where animals urinate frequently.

Manure, which is unprocessed, can be piled and covered, which will reduce the surface heat built up thereby reducing fly breeding. Dry manure does not breed flies, but moisture content of 50 to 80% is where fly breeding occurs and is also where the fly parasites work best.

The eggs of the Fly Parasites are laid inside the flies pupae and the developing flies provide food from within for the young wasps. Also, adult parasites “host feed” by drawing fluid from the fly’s pupae, thus preventing the fly from fully developing.

A generation of fly parasites is completed every 3 weeks yielding a steady reproduction of parasites. An adult wasp lives about 10 days. A fly-free environment should not be expected immediately following the first release if you start after flies are already present. With the geometric increase in populations, a reduction in flies can be expected in 4 to 6 weeks. Fly Parasites will stop pest flies from reproducing, but will not affect existing adult flies, therefore supplemental methods of fly control compatible with Fly Parasites such as traps, sticky paper, or bait stations should be used. Complete instructions are included with each shipment.

Almost every fly breeding hotspot at your location will eventually be killed. Flies still can be migrating in so biological control would work best if the whole neighborhood would use biological control.

Dealer: Fly Exterminators must not be left in direct sunlight or hot areas. A slight increase in ideal temperature range will result in faster emergence.

Customer: If development must be delayed, open the box and hold at 50°F (10°C), 40 – 60% RH, and good air circulation.

Strategic Considerations: Particularly susceptible to pesticides especially when directed at manure. Careful placement of pesticides is important in order to minimize harm. Reduce adult populations with poison baits and spray only adult fly resting surfaces with long residual pesticides.