Many insects can reproduce in livestock manure. These insects may be a nuisance, or they may be of economic concern due to transmission of disease, reduction in growth or production by animals, and contamination of food products. Flies, mosquitoes, and rattailed maggots are frequently of major concern.
Good sanitation is the basis for all fly-control programs. Nevertheless, it is often necessary to supplement sanitation practices with pesticides.
Managing manure properly with good sanitation is the best way to control flies on livestock farms. The fly life-cycle takes about two weeks, one for the larvae to develop and one for the larvae to pupate prior to emerging as an adult fly. Manure is a favorite place for flies to lay their eggs, but wet feed and seepage from silos also are prime areas for fly breeding. Preventing water leaks and seepage from outside sources into the animal housing, feed distribution, and feed storage areas can help to minimize fly breeding. Barnyards should be well drained, and vegetative growth around the facilities should be kept low to minimize areas where flies might breed.
Manure should be removed from animal quarters frequently and stored in facilities that will minimize fly breeding. Many dairy farms use free-stall housing and avoid bedded manure packs, thus less manure remains in the animal housing area for infestation by flies. Also, many dairy farms have changed to inorganic bedding (e.g., sand) in free stalls, which is less desirable for fly breeding than organic bedding. Most swine and poultry operations are enclosed, and manure does not build up in the housing area for swine.
The use of lagoons and pits for manure storage prevents flies from laying eggs in the manure, because there is an inadequate amount or type of biomass to provide ova position stimulant (stimulant that must be present for flies to lay eggs). For stacked manure, moisture should be less than 30% to discourage fly breeding. Coverage of this storage area will limit moisture from precipitation, reducing the risk of run-off and fly infestation.
Fly larvae can still develop in manure spread on the field, but this can be minimized by spreading the manure when conditions are not wet and by thinly spreading the manure to reduce drying time. For totally enclosed animal housing and handling facilities, the structure must be designed to limit entry of flies either by providing airtight facilities or screen doors and windows where appropriate.
An Integrated Pest Management (IPM) program needs to be implemented on every farm. The IPM can consist of a wide array of practices to monitor and control pests. The use of biological and chemical controls needs to be considered in the IPM program. Products are available to control flies on the animals, and pesticides are available for use in the areas of the facility not occupied by the animals. (For more information, refer to OSU Extension Bulletin 473, Livestock and Livestock Building Pest Management, ohioline.osu.edu/b473/index.html, or OSU Extension Bulletin 853, Poultry Pest Management, ohioline.osu.edu/b853/index.html).
The threshold density for determining when to control flies depends on the area where the control measures will be taken. In general, the threshold at homes is very low, and control actions are taken with few flies. The threshold density of the house fly at waste-management sites may be 150 flies per fly paper per 30 minutes.
House flies can be monitored with baited traps, sticky ribbons, or spot cards on livestock facilities. Spot cards are three-inch by five-inch white index cards attached to a fly resting surface. A minimum of five cards should be placed in each animal facility and left in place for seven days. A count of 100 or more fecal or vomit spots per card per week indicates a high level of fly activity.
For successful fly control, organize a control program that best fits your farm. A single pesticidal product rarely gives the most effective and economical control. It is normally best to use a combination of pesticide applications, such as residual wall sprays, space or aerosol sprays, baits, and larvicides, during the fly season.
Because fly resistance is always a possibility, it is best to rotate different chemical-family insecticides, especially when one group begins to lose effectiveness. Consider alternating synthetic pyrethroids with organophosphates. Do not wait for heavy fly populations. It is much easier and less expensive to prevent heavy fly buildup than to control heavy fly populations after buildup. As fly populations begin to build up, take time to treat and treat regularly.
For detailed information on pesticides refer to OSU Extension Bulletin 473, Livestock and Livestock Building Pest Management, ohioline.osu.edu/b473/index.html, or contact your local county office of Ohio State University Extension.
Oral larvicides or insecticides given through the feed prevent the development of flies in manure. Certain states do not recommend the use of oral larvicides or insecticides given through the feed. Oral larvicides are usually fed from May through September. Animals must consume the recommended dosage for the feed additive to be effective. They are not effective against adult flies. Oral larvicides should be used in conjunction with good manure sanitation. A supplemental fly-control program is needed where flies breed in manure from untreated animals or other organic sources.
Feed additives often are not the answer to fly control unless used extensively. All feces must be treated within an area to effectively reduce fly populations. The required treatment area must be several miles across because flies can move readily from herd to herd over an area of several miles within one or two days. This treatment is usually more effective in controlling horn flies and is not very effective against face flies. Feed additives do not control housefly and stable-fly larvae that develop in sites other than fresh manure. Follow label directions and precautions when using oral larvicides and insecticides in the feed.
Manure treatment (larviciding), applied directly to the manure surface to control fly maggots, is discouraged because beneficial arthropods associated with manure can be killed. Also, adding extra moisture to the manure can result in additional fly breeding with increased fly resistance to insecticides. Effort should be made to keep all manure as dry as possible, less than 30% moisture, to greatly reduce or halt fly breeding. However, if manure cannot be kept dry or removed on a weekly basis, it is possible to use manure sprays.
Use a hoe or a trowel to sample the larvae present in manure before treatment. “Hot spots” with high larvae and egg counts can be spot-treated. Apply treatment sprays to wet the manure surface but do not soak. Repeat applications as necessary but not more often than once every seven days. Avoid widespread use of manure sprays, but treating the edges of a covered manure stack may be helpful. Do not apply where animals or birds can come in contact with treated manure. Follow mixing and application directions before use. Do not apply treated manure to crops not approved on the insecticide label.
Biological control is the reduction or mitigation of pests and pest effects through the use of natural enemies. Naturally occurring parasites (wasps) and predators (beetles and mites) in dry manure accumulations undisturbed over long periods of time attack and kill fly larvae and pupa stages. To encourage the establishment of natural enemies, farm operators should avoid excessive use of residual insecticides, especially synthetic pyrethroids.
Fly parasites are tiny wasps that kill fly pupae. They attack only fly pupae in manure and are so small (similar in size to gnats) that they go unnoticed by humans and livestock. Farmers can make frequent releases of small numbers of these beneficial wasps to augment their existing populations of beneficial insects. The wasp females seek out fly pupae, kill them, and then lay eggs within the dead pupae. These eggs hatch and mature into a new generation of beneficial parasitic wasps.
Fly parasites are useful for the control of house flies, stable flies, blowflies, and many other fly species. They cannot sting or bite humans or animals.
Advantages of fly parasites are ease of application and reduced need for chemical pesticides. Using fly parasites also prevents buildup of resistance to chemical pesticides, prevents immature flies from maturing to adult flies, and is cost-effective. With application, there is no equipment, no mixing, and no feed additives. Simply sprinkle them out of the bag onto the manure or staple the opened bag to posts or rafters near areas where fly breeding is a problem.
Although fly parasites are an integral part of a good Integrated Pest Management (IPM) program, insecticides will still play a role in your control program. Insecticide use should be restrained. If biological control agents are to significantly contribute to fly-control programs, they must be integrated with chemical control, manure management, and moisture control to best enhance the beneficial populations. If you have a serious adult fly problem now, it is recommended that you use natural pyrethrins to get the adult population under control before introducing fly parasites. Permethrin is highly toxic to parasites and should be used with caution.
Larvicide use should also be limited, because most larvicides will kill beneficial insects as well. However, if you have a “hot spot” of heavy fly larvae, larvicides can be used without inflicting much damage on the overall beneficial insect population. Insect Growth Regulator (IGR), such as cyromazine (Larvadex) approved for poultry operations, does not affect beneficial insects. It only kills the fly larvae. This is the only larvicide that does not harm beneficial insects and can safely be applied to the breeding site without fear of destroying the beneficial insect populations. Sticky paper, tapes, or ribbons and bait traps will help reduce the adult fly population without hurting the natural enemies.
Weekly removal and spreading of manure disrupts the fly life-cycle and prevents new adults from emerging in and around the barn. Removing the manure also helps the parasitic wasps, which find fly pupae more easily if the depth of the manure is relatively shallow. Leaving some surface manure behind when you clean out will keep the new generation of wasps in the barn.
Flies have the ability to produce more eggs, produce a new generation in a much shorter period of time, and travel much greater distances than fly parasites. Consequently, it is best to release small amounts of fly parasites throughout the fly season rather than just one large release. Make weekly releases of 250 wasps per animal from mid to late May to August or September. Some farmers practice the release of 200 parasites per milking cow or 1,000 parasites per calf. Commercial farms that generate large quantities of manure should import fresh parasites weekly. For small farms, choose a biweekly, triweekly, or monthly schedule.
Many companies who sell parasites advertise their products in farm magazines but not all of them sell the right species adapted for the Ohio climate. Dairy farmers should purchase Muscidifurax raptor and avoid Nasonia vitripennis. Existing data indicates that in the Midwest the recommended species are as follows:
| Fly Parasite Species | Flies Attacked |
|---|---|
| Muscidifurax zaraptor | House fly pupae preferred. Also attacks stable flies. |
| Comments: Muscidifurax zaraptor stays nearer the surface where house fly pupae are more commonly found. Populations peak in summer, often July and August when the fly population peaks. This species is often the dominant parasitoid species in Midwest feedlots. Considered best against house fly pupae. Early season spring releases show promise. M. zaraptor moves out evenly from release sites, killing off concentrated house fly populations within 50 feet of release sites. | |
| Muscidifurax raptor | House and stable fly pupae |
| Comments: An outdoor species that also works indoors. M. raptor prefers dry, dark habitats and is active almost year-round, preferring cool temperatures and readily reproducing on late-season freeze-killed fly pupae. It has the potential to parasitize 20 fly pupae per day for one to four weeks. Early-season inundative releases have been helpful against house flies. M. raptor populations increase in late September and October when temperatures drop. | |
| Spalangia nigroaena | Stable fly pupae preferred. Also attacks house fly, horn fly, little house fly, dump fly, false stable fly, etc. |
| Comments: Works well against both stable flies and house flies. S. nigroaenea digs deep into manure where stable fly pupae are found. Parasite release costs are usually offset by reduction in insecticide treatments. In research trials, dairy farmers using fly parasites have made as much as 80% fewer insecticide treatments with 50% lower fly populations than with conventional insecticide control. There is still much to learn on using fly parasites most effectively in fly management programs. | |
| Sources: Featured Creatures: House Fly. (EENY-48). University of Florida, Institute of Food and Agricultural Sciences. 1998. creatures.ifas.ufl.edu/urban/flies/house_fly.htm Livestock and Livestock Building Pest Management. Ohio State University Extension Bulletin 473. ohioline.osu.edu/b473/index.html |
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Water management that prevents mosquito breeding is essential for effective control. Eggs do not hatch unless they are in water. Locate standing water on premises and eliminate it if possible. Drain or fill stagnant water pools, puddles, ditches, or swampy areas around the facility. Tires, in particular, require special mention because they are ideal breeding places for vector mosquitoes. Stagnant ponds, which are highly septic, and waste lagoons also can be breeding areas for a large number of mosquitoes. Mosquito larvae live around the edges of ponds and waste lagoons. A waste lagoon with a heavy crust will shelter fewer mosquitoes than a waste lagoon with floating scum and floating debris. Excessive amounts of emergent aquatic vegetation will also shelter mosquitoes.
Follow these steps to reduce mosquito breeding areas:
For more information on mosquito species and control procedures, including chemicals, refer to Ohio State University Extension Bulletin 641, Mosquito Pest Management, ohioline.osu.edu/b641/index.html, or contact your local county Extension office.
Frequently during the warm summer months, rattailed maggots are reported as a nuisance. These creatures are not a problem as long as they remain in the liquid manure pit; however, they are known to move out of the pit or lagoon in large numbers, contaminating livestock feed, accumulating in electrical boxes and causing short circuits, and congregating in stacks of egg cartons and other unwanted places. The maggots migrate to a drier place for pupation.
Rattailed maggots, known as the larval or immature stage of syrphid flies, are about 1-1/4 inches long. The body portion is about three-fourths of an inch long, and the tail portion (breathing tube) one-half inch long. These maggots are white-colored with the body portion an elongated, oval, cylindrical shape, which is wrinkled and semitransparent, protracting into a long breathing tube (tail).
These larvae of the Syrphid fly live in highly polluted water, such as livestock lagoons, abandoned fish pools, foul pools, and streams associated with barnyards, etc. Maggots are able to live in the water, if sufficient solids are present as food. The adult flies resemble honey bees in appearance and are often seen “hovering” near the ground in the barnyard. These flies do not bite or sting humans and are considered beneficial because they kill aphids.
Non-chemical treatment. Since this maggot breeds and feeds in highly polluted waters, efforts must be made to keep the lagoon in the optimum condition, promoting a more nearly ideal anaerobic condition. Never allow accumulations of manure above the water line, either floating or sticking to the sides, because these conditions enhance fly development. Keep the banks steep and weeds under control.
Use loose soil and construct a soil barrier between the milk house and the rattailed maggot source. As maggots migrate to the soil barrier, they will dig into it to pupate rather than move into the milk house. Try to agitate the pit contents frequently during the spring and summer by pumping the pits routinely (at least once a week) to disrupt maggot development. Always maintain a waterline above the manure solids and clean out the pit contents on a routine basis.
Chemical treatment. Unfortunately, there are no good pesticide control measures. There has been some success by layering either Ravap or Larvadex larvicide on the liquid and manure surface. Read the label for application instructions and safety guidelines. For best results, do not agitate the pit contents after application. The pesticides are typically mixed with fuel oil, which clogs the long breathing tube of the rattailed maggot, similar to oils applied to the surface of stagnant, non-moving water to kill mosquito larvae.
Control of rodents around livestock structures is best accomplished by minimizing their access to a food supply. Farmers control rodents by proper storage of feed, proper disposal of spoiled feed, and limiting areas attractive as living quarters for rodents. The presence of rodents in enclosed livestock facilities can be minimized by proper design of structures and use of proper methods to eliminate rodents that do enter the facilities. Farmers must control rodents to minimize costs caused by feed loss, damage to livestock and feed structures, and spread of disease carried by rodents. Rats can get through a 1/2-inch hole, and mice only need 1/4 inch. Rats drink water three times a day and feed nocturnally twice a day.
Rodent-proofing must include protective devices on pipes, electrical cables and conduits, drains, and other equipment where rodents travel. In addition to preventing access to buildings along these routes, attention must be given to reducing shelter and food and water sources that rats and mice use. Both rats and mice use drainage pipes or sewage systems as routes to enter buildings. Equip floor drains with metal grates fastened securely in place. Use grate openings that are 1/4 inch across or less.
Manure management systems in livestock facilities may be of a type where manure water is periodically drained from the building to a lagoon or other storage area. Extend discharge pipes far enough over the bank or into the lagoon to prevent rodents from jumping or crawling into the open end. Install rodent shields or use a downward-turned elbow to prevent rodents from gaining access.
A “floating” metal cover at the open end of the discharge pipe, with a hinge at its upper edge, can also be effective. The hinge must operate easily so water or manure will open the cover, but the cover must fall back into the closed position when the flow stops. These covers sometimes freeze shut, so they must be checked regularly. Always cap pump-out ports for manure storage pits when they are not in use. When left open, they allow easy entry to rodents.
Bait Stations for Controlling Rats and Mice, (G94-1215-A), NebGuide, University of Nebraska. ianrpubs.unl.edu/wildlife/g1215.htm
Controlling House Mice, (G92-1105-A), NebGuide, University of Nebraska. ianrpubs.unl.edu/wildlife/g1105.htm
Controlling Rats, (G92-1106-A), NebGuide, University of Nebraska. ianrpubs.unl.edu/wildlife/g1106.htm
Rodent-Proof Construction, (G94-1217-A), NebGuide, University of Nebraska. ianrpubs.unl.edu/wildlife/g1217.htm