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Jeffery K. Tomberlin | Assistant Professor and Extension Entomologist
Bart Drees | Professor and Extension Entomologist
Texas A&M University System
The poultry industry contributes about $1.6 billion each year to the Texas economy, including the production of more than 627 million broilers and about 4.7 billion table eggs in 2005. In 2003, the U.S. Department of Agriculture ranked Texas sixth in the nation in broiler production and seventh in egg production.
One of the largest management problems facing poultry producers is pest control. Poultry operations can be infested by ﬂies, mites, lice, bed bugs, ﬂ eas, beetles, red imported ﬁ re ants, chiggers and gnats. But by implementing integrated pest control measures, producers can minimize the damage from these pests.
For speciﬁ c suggestions on products to consider for suppression of these pests, see Tables 1 and 2 (page 14) by downloading the full PDF.
The shift from many small farm ﬂocks to fewer large poultry operations has greatly increased ﬂ y problems by creating concentrated breeding areas and large amounts of waste that are costly to be removed often. As more people move to rural areas, poultry producers face increasing pressures to reduce ﬂy populations. Populations of manure-breeding ﬂies may cause a public health nuisance, resulting in poor community relations and threats of litigation. To achieve an acceptable level of ﬂ y control, a dedicated effort is necessary.
Several kinds of ﬂies are common in and around caged layer houses in Texas. Probably the most common ﬂies are the house ﬂy and the little house ﬂy. About 95 percent of problems involve the house ﬂy. Both of these ﬂy species can move up to 20 miles from the site of development, but they normally ﬂy no more than a mile or two from the initial source.
House ﬂies, Musca domestica, are about 1⁄2 inch long. They breed in moist, decaying plant material, including refuse, spilled grains and spilled feed and in all kinds of manure. For this reason, house ﬂies are more likely to be a problem around poultry houses where sanitation is poor. Adult house ﬂies prefer sunlight and are very active, crawling over ﬁ lth, people and food products.
This ﬂy is the most important species because it can carry and spread human and poultry disease agents and leave ﬂy specks on eggs. For example, the house ﬂy is the intermediate host for the common tapeworm in chickens, and it has been implicated in the transmission of several viral and bacterial pathogens of people and animals.
The little house ﬂy, Fannia canicularis, is somewhat smaller than the house ﬂ y, about 3⁄16 inch long. This ﬂy prefers a less moist medium for breeding and reproduction than does the house ﬂy. The little house ﬂy chooses poultry manure over most other media for egg-laying.
The adult ﬂy also prefers shade and cooler temperatures and is often seen circling aimlessly under hanging objects in the poultry house, egg room and feed room. Large numbers of the ﬂies may also hover in nearby garages, breezeways and homes, which offer shade and protection from wind.
Although the little house ﬂy is less likely to crawl on people and food, it does spark com-plaints about ﬂy problems from people living near poultry establishments, and it may surpass the house ﬂy in its ability to cause a nuisance to nearby homeowners.
The black garbage ﬂy, Hydrotea ignava, is shiny bronze-black and slightly smaller than the house ﬂy. The wings are held straight back. This ﬂy tends to remain on its food source at night rather than resting on the ceiling or on outdoor vegetation, as does the house ﬂy. The female ﬂy does not seem to ﬂy great distances, but it has been found about 5 miles from its breeding area.
Although black garbage ﬂy larvae have been known to exterminate house ﬂy populations, they should not be considered entirely beneﬁcial because these ﬂies also can build large populations on the farm and ﬂy to nearby communities. All stages are found throughout the year under suitable conditions, and they can tolerate cold weather. The life cycle is similar to that of the house ﬂy.
Blow ﬂies, sometimes known as green or blue bottle ﬂies, are slightly larger than house ﬂies and sometimes live in poultry houses. These ﬂies may be green, blue or nearly black, which makes for easy identiﬁ cation. Blow ﬂies prefer to breed and reproduce in decaying animal and bird carcasses, dog manure, broken eggs and wet garbage. Generally, a good sanitation program and rapid mortality processing will hold these ﬂies in check. Other ﬂies found on the poultry establishment include soldier ﬂies, small dung ﬂies, fruit ﬂies, and rat-tailed maggots.
To control ﬂies most effectively, at the lowest cost and with the least harm to the environment, it helps to understand their biological life cycle. All ﬂies develop through four life stages: egg, larva, pupa and adult.
Most adult ﬂies lay small, white, oval eggs on the breeding medium. Creamy white larvae (maggots) develop in moist materials. Mature maggots crawl out of this material and move to a drier place for the pupal stage. The brown, seed-like pupae ﬁnally yield adult ﬂies.
Development from egg to adult ﬂ y may take just 7 to 10 days under the ideal conditions often present in poultry manure pits.
The most effective way to control ﬂies is by manure management. As many as 1,000 houseﬂies can complete development in 1 pound of breeding material. Fresh poultry manure contains 75 to 80 percent moisture, which makes it ideal for ﬂy breeding.
You can practically eliminate ﬂy breeding in this material by reducing the moisture content to 30 percent or less. Drying manure is preferred because once dried it will occupy less space, usually has less odor and is more easily transported off-site. Also, high-moisture manure often results in high black garbage ﬂy populations.
Dry manure management
To prevent ﬂy breeding, remove the manure often, at least twice a week. This breaks the breeding life cycle. It is important to scatter the manure in thin layers outdoors to kill the eggs and larvae by drying them. Avoid piles or clumps of manure.
You must have access to enough land so the manure can be spread thinly; this keeps excessive amounts of nutrients from building up in the soil. Spread it at an agronomic rate for your area.
If the manure is stored in-house, it must be dried to a 30 percent moisture level and be maintained at this level. Dry manure can be held for several years. Any practice that limits moisture in the droppings or aids in rapid drying is important for ﬂy control.
To control ﬂies, it is vital that you lower the water content of the manure. Follow these steps to minimize water content:
- Prevent leaks in water troughs or cups. Regulating water ﬂow to an on/off cycle may help eliminate moisture problems. Assign an employee to walk the manure pit daily to check for leaks.
- Provide abundant cross-ventilation beneath the cages, especially during hot weather. Using 36-inch pit fans blowing across the manure can be very effective. Place a curtain above the manure every 100 feet to help keep the air moving over the manure. Adequate house ventilation is important at all times.
- If the water table in your area is high or if there is a danger of water running into the house from the outside, adjust the ﬂoor grade so that the house ﬂoor is higher than the outside surrounding ground. Direct surface water away from the building. Drain and ﬁll all low areas around the houses.
- Prevent dysentery by keeping the water clean. If dysentery develops, use recommended antibiotics.
- Prevent excessively high house temperatures, which encourage the chickens to drink abnormal amounts of water.
- Practice good husbandry by restricting ex-cess water consumption but not to the point of reducing egg lay.
- If your resources allow it, consider adopting a new housing system designed to dry the manure in the pits.
The most important aid in successful ﬂy control is sanitation. Often, certain conditions in and around the poultry operation will encourage ﬂy outbreaks. These must be eliminated.
To improve sanitation:
- Quickly remove and dispose of dead birds and broken eggs. Dispose of them far from the poultry premises by burning them in an incinerator or by using another approved management method.
- Immediately clean up and dispose of feed spills and manure spills, especially if they are wet.
- Clean out weed-choked water drainage ditches.
- Install proper eave troughs and down-spouts on poultry houses to carry rainwater far from the buildings. Provide proper drainage in the poultry yards.
- Minimize the migration of ﬂies from other ﬂy-infested animal operations close to the poultry house.
Entomologists encourage the use of biological control in poultry houses. If you are considering biological control for your operation, be sure to buy beneﬁcial insects (also called “beneﬁcials”) that are adapted to the climate in your area and apply them as directed by the supplier. Neither the suppliers nor Texas Cooperative Extension guarantees success for the implementation of biological control efforts, particularly when initiated after the appearance of high ﬂ y populations.
These beneﬁcials are ﬂ y parasitoids, actually very tiny wasps, and are the naturally occurring enemies of manure-breeding ﬂies. They kill ﬂies in the pupal stage.
One species, Spalangia nigroaenea, is about the size of the head of a house ﬂy (1⁄16 to 1⁄8 inch) and lives in the manure. An adult female wasp lays an egg on the ﬂ y pupa within the puparium (the hard, brown case containing the ﬂ y pupa). Then the developing wasp larva consumes the pupa and emerges as an adult.
These ﬂy parasitoids are speciﬁc to ﬂies and attack nothing else. They do not bite or sting people or birds and usually go unnoticed by those living near poultry operations. They self-propagate in the process of controlling pest ﬂies.
However, mass releases are usually needed. Also, the wasp lays fewer eggs than does a ﬂy over the same period, making it necessary to start with an initial wasp release and follow up with supplemental releases weekly. Release these wasps before and during the ﬂy season until control is achieved. Under proper management, suppression occurs in 10 to 20 weeks.
Whenever you use beneﬁcial insects, be very careful when applying insecticides. Minimize chemical sprays where these wasps are released. And never treat the entire manure surface with insecticides, except for cyromazine (Larvadex®); otherwise, the beneﬁcial insects, as well as the pest ﬂies, will be killed.
To use chemicals without killing all the beneﬁcials, spot-treat the manure where the ﬂy larvae are concentrated and apply pesticides to ﬂy-resting sites, such as walls and structural posts.
You can improve the chances of successful biological control with these wasps by following a strict sanitation program of manure management, water management and weed mowing. Keep the manure dry because wet manure pro-motes ﬂ y breeding and inhibit beneﬁcial insect breeding.
Other beneﬁcials in poultry manure include mites and beetles, according to Pest Management Recommendations for Poultry, a publication by Cornell University and Penn State Cooperative Extension. Mites and beetles are major predators in caged-layer operations.
The macrochelid mite, Macrochelis muscaedo-mesticae, is reddish-brown and less than 1⁄16 inch long. It feeds on house ﬂy eggs and ﬁrst-instar (or ﬁrst-stage) larvae. Found on the outside layer of manure, this mite can consume up to 20 house ﬂy eggs a day.
Another mite, the uropodid mite, Fuscuropoda vegetans, feeds only on ﬁrst-instar house ﬂ y larvae deeper in the manure. Both species occur naturally in most poultry facilities.
A hister beetle, Carcinops pumilio, is black and about 1⁄8 inch long. It feeds on house ﬂy eggs and ﬁrst-instar larvae. Common in both broiler and layer houses, it can consume 13 to 24 house ﬂy eggs per day. Both adult and im-mature hister beetles live in the surface layers of manure.
Another hister beetle, Gnathoncus nanus, is present at lower numbers on poultry farms.
In Texas, the use of ﬂy parasitoids for biological control may reduce the chemical residues for people, birds, eggs and the environment. However, to date, claims that wasps can pro-vide long-term ﬂy control have not always been backed by scientiﬁ c research results.
Biological control methods are more effective if the manure is kept dry. Leave accumulations of poultry manure undisturbed over long periods to support large populations of native ﬂy parasitoids and ﬂy predators (beetles and mites). Be sure to encourage the native strains of beneﬁcials already present in the dry manure to populate.
Remove manure only during the ﬂy-free time of the year, minimize residual insecticide sprays (residual insecticides leave a residue that remains effective for some time after application) in the manure pits and use pyrethrin sprays as a ﬁrst option for adult ﬂy knockdown.
Many types and styles of ﬂy traps are available, including sticky ﬂy strips, funnel-type traps and “ﬂy zappers,” which use black lights with electrically charged grids to kill the insects. Some traps are baited with a ﬂy attractant material.
Traps appear to help as a preventive measure in tight, enclosed areas such as egg rooms where there is no breeding ﬂy population and where good sanitation practices are followed. However, in areas of heavy ﬂy populations, traps do not reduce ﬂy numbers to satisfactory levels. When used, traps operate during the night, away from doors and windows.
One should judge a trap by the population of ﬂies remaining in the area and not by the number of ﬂies caught in the trap. Most entomologists believe that ﬂy traps used alone are ineffective in controlling ﬂies, especially in and around livestock and poultry operations.
In sensitive areas, a fan might be used to blow air through a screened doorway from the egg room or other work area into the main poultry house. Flies will not move against the wind into the egg room or other work area. Commercial electric-powered air curtain fans are available. However, certain state health departments may require solid doors between the egg room or other main work areas and the main poultry house.
To make informed control decisions, it is important that you monitor the ﬂy populations. Visual observations alone can be misleading. Historical observations may be helpful in determining when to apply control options such as manure removal or the release of beneﬁcial arthropods.
Surveillance methods include moving tape counts, sticky ﬂy tapes, ﬂy speck counts, baited jug traps and larval sampling.
A moving tape count is the best surveillance method, requiring about 5 minutes each day walking on a 1,000-foot walk to catch 25 to 75 ﬂies. Walking down and back in each house is cheap and easy.
Carry the sticky ﬂy tape using the same walk pattern at the same time of day. If possible, do not turn on or use a light, as this encourages ﬂy movement.
Sticky ﬂy tapes that hang often tell nothing. Tapes in a chicken house ﬁll up fast during the summer. However, they do enable you to determine the ﬂy species infesting the operation.
Some operators hang sticky ﬂy ribbons along the aisles. Each week they count the captured ﬂies and replace the tapes. A weekly count of 100 ﬂies per ribbon may indicate that ﬂy control is required.
Ribbons may become ineffective after 2 to 3 days because of dust and ﬂy covering. Tapes are messy to use, and location is important. These devices are a poor choice for a monitoring program.
Flyspeck counts are an economical way to determine whether ﬂy-control methods are needed. Fasten 3- by 5-inch white index cards, ﬂush against feed troughs, ceilings, braces or other ﬂy-resting areas, and leave them for several days to a week. Label the back of each card with the date and location in the facility.
Place the cards on the head rafters (ten cards per house) and count the ﬂy specks on one side. Count the “ﬂy specks” on a given date or over a period of time within a given house. Change the cards once a day or week, depending on the populations present. Fifty or more spots per card per week may indicate that ﬂy-control measures are required.
Place new cards in the same position each week. Fly species cannot be determined from the spots.
Baited jug trap. More expensive than other sampling methods, baited jug traps can indicate changes in and need for control of house ﬂy populations. This trap will not collect species as such as the lesser house ﬂy because they are not attracted to the commercial baits available.
To make a jug trap, cut four access holes (2 to 6 inches in diameter) around the upper part of a plastic milk jug. Attach a wire to the jug and pour commercial ﬂy bait (about 1 ounce) inside the jug bottom. For increased effectiveness, add the ﬂy pheromone muscalure (Muscamone®). Hang the jug about 6 feet above the ﬂoor around the pit periphery.
Larval sampling. It is most important to walk the pits to determine “hot spots” where the manure appears ﬂattened and wet and contains heavy populations of ﬂy eggs and maggots. Always take a hoe or trowel to sample for larvae. Keep the pits walkable, clean and water-free.
“Hot spots” usually appear where water has accumulated in the manure. Some producers carry knapsack sprayers to treat only the hot spots to halt excessive ﬂy larval breeding. However, treating manure widely and excessively will kill the beneﬁcial agents.
The northern fowl mite, or feather mite, Ornithonyssus sylviarum, is a very important external parasite of poultry. Heavy populations of this mite can reduce egg production by 10 to 15 percent. The mites can also annoy egg handlers and other people.
Mites are often noticed ﬁrst on the eggs. Check for mites ﬁrst on the vent, then on the tail, back and legs of layers. Feathers become soiled from mite eggs, cast skins, dried blood from feeding and excrement.
The eight-legged adult is about 1⁄26 inch long and dark red to black. The mite’s entire life cycle—egg, larva, several nymph stages and adult—is completed on the bird and can be completed under ideal conditions within a week.
If you detect the mites early, you may need to treat only some of the caged layers. Each week, monitor at least 10 randomly selected birds from each cage row in the entire house. Mite populations will increase in cooler weather.
The chicken mite, Dermanyssus gallinae, sucks blood from poultry at night and remains secluded in cracks and crevices during the day. Poultry workers entering poultry houses at night may be readily bitten by these mites as well. When the mites are numerous, weight gains and egg production can be reduced. These red and gray mites are difﬁ cult to see without a magnifying glass. The life cycle may be completed in 7 to 10 days during warm weather; they are inactive during cold weather.
Female scaly-leg mites, Knemidocoptes mu-tans, are small with round bodies and short, stubby legs. These mites must be magniﬁed to be seen because they are only 1⁄50- to 1⁄100-inch long. Young mites are at ﬁrst six-legged, then molt through two eight-legged nymphal stages.
The scaly-leg mite is distributed widely throughout the world, but its exact range in Texas is unknown. This mite attacks poultry, commonly chickens and turkeys. However, infestations of commercial poultry are uncommon, as these birds are typically young and have not had contact with older birds that may be infested with these mites.
The scaly-leg mite also has been reported on pheasants, partridges, bullﬁnches, gold ﬁnches and many passerine (perching) birds. Researchers suspect that wild birds transmit the mites to domestic ﬂocks.
Little is known about the life history and habits of this species. The females burrow un-der scales on the feet and legs of poultry and deposit eggs. They begin laying eggs soon after they burrow under the skin and continue to oviposit (lay eggs) for about 2 months.
The eggs hatch in about 5 days into six-legged larvae that soon molt into nymphs. The nymphs develop into mature males and immature females. The immature female becomes a mature egg-laying female shortly after it is fertilized. Complete development for an egg-laying female probably requires 10 to 14 days.
When the mites burrowing under the scales on the feet and legs of poultry, a powdery mate-rial accumulates and binds into a scab of serum discharge. Affected feet and legs usually have red blotches. Glands in the mouthparts of mites may secrete an irritating ﬂuid that causes the discharge and blotches. Eventually, the feet and legs may be covered with these crusts or scabs. Mites remain beneath the crusts in small oval vesicles.
Irritation from mite infestation causes the poultry to pick at the crusty formations. As the formations extend over the feet and legs, they interfere with joint ﬂ exion and cause lameness. Severe infestations may cause loss of toes, loss of appetite, lowered egg production, emaciation and death.
The depluming mite, Neocnemidocoptes laevis gallinae var. gallinae, is similar to the scaly-leg mite but is smaller and more oval. Infestation occurs throughout the United States. Hosts include pigeons, pheasants, geese, canaries and chickens. Many wild birds have been infested with this species or with closely related, un-identiﬁ ed species.
Development stages include egg, larva, nymph, male adult, and immature and mature female adult. Little is known about the life history of this species, but researchers believe that the transformation from immature to mature female occurs after fertilization.
The fertilized female begins depositing eggs within a few hours after starting to burrow and continues at 2- or 3-day intervals for about two months. The eggs hatch in about 5 days. Development from egg to egg-laying female requires 10 to 14 days. Fewer than 10 percent of the eggs mature into adults.
The depluming mite burrows into the skin at the base of the feathers on the back, on top of the wings, around the vent and on the breast and thighs. It causes intensive itching, often resulting in feather pulling. The fowls may lose feathers over large areas of the body. The infestations are especially noticeable in spring and summer; they may disappear in autumn.
For more information and pesticide recommendations, download the full PDF.