Question of the Week
Answer: I am pleased to provide you with information on organic parasite control in cattle.
Flies of concern may include members of the family Muscidae that includes house flies, stable flies, horn flies and face flies. Although certain flies favor barns or confinement settings and others are found more in pasture, some eat filth, others such blood and others feed on secretions, all flies reproduce rapidly and can cause trouble that it is worth the effort to prevent. The life cycle is complete metamorphosis: depending on conditions, fly eggs may hatch in a day. Fly larvae (maggots) pass through three larval instars and a pre-pupal stage within about a week, and adult flies begin laying eggs within a couple days.
These flies are pests because at a minimum they cause animals discomfort, and are estimated to reduce weight gain by 25% (18) and decrease milk production up to 15-30% (15) or even 40-60% (18). Flies can transmit all manner of diseases (2) including bacterial diseases such as cholera and anthrax, and eggs of parasitic worms (10). The threshold that indicates a high level of activity for stable flies is just 10 flies per animal. Other flies not discussed here include external parasites that live part of their breeding cycle on/in animals.
The most economic and practical method of controlling flies is to reduce their breeding. The most effective way of reducing fly breeding is to eliminate areas that provide fly habitat where larvae feed and develop in wet or moist manure and other decaying organic matter. Observe the area where flies are a problem and figure out where the flies are breeding. Different flies have slightly different life cycles for breeding as well as different habits for being pests on animals. All the other approaches listed below are complimentary, and will be most effective when used together with good sanitation.
Reduce fly breeding areas around barns and buildings
• Remove or move manure, bedding, waste and other sources of food for fly larvae. For most flies, the breeding cycle may range from 10 to 60 days (shorter in warm conditions and longer when the weather is cool). Move fresh manure, bedding and spilled feed and from barn areas every 2-3 days (10) if possible to break this breeding cycle.
• Keep animal barns and yards dry. Repair any leaky pipes promptly. Address any other sources of water that may help create areas that are ideal places for flies to lay eggs and their larvae (maggots) to develop. Clean drainage ditches. Cover silage.
• Keep drinking water fresh and clean. Dump water where it will be used by plants or dry quickly. Avoid creating places that stay soggy.
Keep flies out
• Ventilate barns to maintain good air circulation.
• Put up physical barriers such as screening on windows, and keep doors closed whenever it is practical.
Reduce Fly Breeding areas in Pasture
• Manage pastures using strategies such as rotational grazing to interrupt pest life cycles. Fly eggs, maggots, pupae and adults all die after a while.
• Disperse, break up and dry out manure paddies by dragging a harrowing. This is especially important early in the season before populations multiply.
• Encourage dung beetles by avoiding pesticides such as synthetic parasiticides (Ivermectin) or using them judiciously. Dung beetles break apart and incorporate fresh manure into the soil, eliminating breeding areas and thus reducing horn fly populations.
• Incorporate pastured poultry into your garden, pasture or farming system to eat fly larvae and help keep populations down. Both domesticated and wild birds in animal pastures, including chickens, ducks, geese, guinea hens, and cattle egrets will pick through paddies and eat fly eggs and larvae. Chickens are even adept at catching adult flies. Eggs or other poultry products may be an enterprise for farm income diversity.
• Compost organic materials using aerobic methods. A hot compost pile (where heat is generated by decomposition) will kill fly larvae, and presents an inhospitable place for adult flies to lay their eggs.
Fly traps: many possible designs and variations are allowed for use in organic production
• Indoor traps include sticky traps or fly tape. Place these near beams and walls so they do not catch bats, and away from any barn swallow nests. Pheromone traps may be more effective against certain species of flies.
• Outdoors-an inverted cone traps consist of a cone with a hole in the top that opens into a space enclosed with screening from which flies cannot escape. Smelly bait under the cone will attract flies so they fly up through the hole in the top of the cone into the enclosed space where they die. These traps should be placed in full sunlight, sheltered from strong winds, and within 6 feet of active breeding areas, such as at the ends of barns manure piles or calf hutches.
• Walk-through traps can help reduce flies—especially horn flies--on larger animals. Strips of canvas dislodge flies from animals’ backs and sides. Attracted to the light, they fly up and become trapped between two layers of screened mesh. Plans are available from various sources including ATTRA. Please note that some plans for walk-through fly traps recommend the use of treated lumber. Organic producers must find alternatives to using this prohibited material. Please see ATTRA’s publication entitled Organic Alternatives to Treated Lumber. Walk-though traps can be placed anywhere where animals must pass, such as the entrance to the milking barn, and to sources of water. While cattle may need to be trained to walk through such an unfamiliar space at first, they may later walk through to achieve its benefits even when it is freestanding in a pasture.
• Use bug zappers to kill adult flies. These are most effective when the bulbs are replaced frequently enough to keep the ultraviolet wavelength attractive to insects. Keep records of their date of installation; a light that appears all right to the human eye may not maintain that proper wavelength.
• Recognize and encourage predators: Hister beetles are small, shiny black beetles that eat fly eggs—one beetle can eat as many as 24 eggs per day. Predatory mites also eat fly eggs and small maggots (15).
• Release fly parasites such as parasitic wasps. The Cornell website on biological notes the use of the parasitic wasp Muscidifurax raptor for control of the housefly Musca domestica and stable fly Stomoxy calcitrans, as well as different types of bacteria, fungi, and nematodes for flies. The wasp Muscidifurax raptor may be most effective in hot and humid conditions. Other wasps or mixtures of wasps may be more effective in other areas. Consult with an insectary or supplier of beneficial insects about which parasitic wasps are most appropriate for your species of fly, type of livestock and region. A supplier should also be able to provide recommendations on the best conditions, locations, frequencies, and numbers of releases. Remember to protect these beneficial insects from getting too hot, cold, wet or dry. Releases may be most effective when done weekly, and will probably need to be done every year because their numbers decline in winter.
The ATTRA publication Farmscaping to Enhance Biological Control includes a description on page 7 of birds and bats as insect eaters (biological control agents), and its Sources of More Information section includes sources of bat houses. Please see also the article (C ) that describes one person’s experience with using releases of parasitic wasps for fly control around goats. Release of predators is reported to be quite cost-effective.
• Provide habitat for bats, and birds such as purple martins (in the parts of the country where they live). Several species of bats and birds will inhabit appropriately constructed and well-placed nest boxes or other types of enhanced or artificial housing, and help by eating flies.
Some pesticides are allowed for use in organic production a complement if other methods are unsuccessful or insufficient. Such materials should be used to complement, not substitute for other methods as listed above. Before you use any organic or biological pesticide, you must include it in your organic system plan that is approved by your organic certifier. Botanical and allowed synthetic pesticides may be found in various product formulations at feed stores and farm coops. Organic or natural materials often have inert ingredients or synthetic carriers that are not allowed. Botanical pesticides also need to be labeled for use on cattle or other animals where you intend to use them. All synthetic pesticides, including insecticidal ear tags, are prohibited in organic production. It is good to check with your veterinarian to see if she or he has any experience in administering organic pesticides in animal production.
Lice are classified into two main orders, described in more detail below. Both orders are fairly specific in their host relationships. They spend their life cycle on their host, and are spread by direct contact.
Chewing lice (Order Mallophaga) feed on feathers, hair, skin, and other external tissues of animals. They are often referred to as bird lice, because they thrive in bird feathers and may puncture the skin at the base of feathers. Bovicola bovis is the species that most often affects cattle.
Sucking lice (Order Anoplura) are blood-sucking insects that are found on mammals only, not on birds. Important parasites, they live on mammal blood and can transmit diseases. Legs are good at grasping the hair of their hosts. Their mouthparts have styles that pierce the skin and small hooks hold on while they are feeding. Please see the more detailed description of the life cycle of lice in the article (B) about lice on goats.
According to Organic Valley Co-op, in a webpage entitled Controlling External Parasites on the Organic Farm (5), important lice pests of cattle include one species of chewing louse and four species of sucking lice. They affect cattle by causing irritation, blood loss, loss of appetite, and decreased gain. Factors associated with infestations are close confinement and cold weather. Control measures are similar for chewing and sucking lice. The life cycle of cattle lice is about 24 (3) to 30 (12) days. Reproduction increases in winter, such that young dairy animals can be heavily infested with lice (3). Eggs hatch in about 7 days (10). Because most treatments will not control eggs, they will need to be repeated to kill the new eggs that hatch out. Check animals at 14-day intervals to determine if the infestation has been eliminated or brought under control (3).
Prevention is the most important. If an infestation appears, treat it promptly with the control options that are allowed in certified organic production. Most of the ideas below come from the Organic Valley reference (5).
• Prevent infestations by isolating and observing any new animals for three weeks.
• Prevent direct contact between healthy animals and those that are infested with lice.
• Provide good quality feed with appropriate mineral supplements. Offering minerals free-choice allows cattle to meet their own needs (5). Provide free choice kelp to young stock in winter to reduce lice (9).
• Reduce animal stress by following all the requirements in the organic standards, especially including access to the outdoors, pasture for ruminants, fresh air, direct sunlight, shade, shelter and the opportunity to exercise.
• A thin coat of vegetable oil in the affected area will suffocate insects (5) and can probably kill insect eggs. Another resource suggests raw linseed oil applied with a stiff brush (8). The application technique sounds effective for application. Since the effect of oil is physical, any natural vegetable oil should work and be allowed.
• Soap dissolves the waxy cuticle (5)(9) or exoskeleton of lice. Repeat in one week to get the lice from newly hatched eggs. Please note that this is not a recommendation for special lice shampoos. Any type of soap will harm insects. Just choose one that will not be too irritating to your animals.
• Liquid enzymes dissolve the insect’s exoskeletons (5). Be sure these are natural enzymes derived from non-pathogenic bacteria or fungi, or from edible, non-toxic plants, and not genetically modified (11)
• Diatomaceous earth has naturally pointed edges that pierce insects’ exoskeletons (5). Be sure to use natural, non-heated forms (11), not the type that is sold for pool filtration (5).
• Use garlic powder as a topical treatment and feed as a tincture. Garlic containa allicin that acts as an insect repellant and antimicrobial (5).
• Rub white hellebore root on the affected area, or make a liquid mix of 4 quarts boiling water and 4 oz. white hellebore and wash the animal’s effected parts when the mix has cooled down (7).
• Various other herbal preparations are described in (8) including pyrethrum powders; Essential oils such as anise, camphor, eucalyptus, pennyroyal, pine rosemary & sassafras: 1 part of each with 2-3 parts olive or other oil. Rub in well. (Grainger and Moore, 1991); Wash morning and evening with powdered lobelia seeds (2 oz. in 1 qt. boiling water). Let stand a few hours and apply with sponge. (Dadd, 1897, p. 196); Raw linseed oil applied with a stiff brush (Alexander, 1919, p. 74 and Udall, 1943). Please check with your certifier to be sure all of the ingredients mentioned in these treatments would be allowed.
The website of Farmer Research in the Northeast describes the problem of lice as follows, and proposes a research project. The results are not yet posted. You may wish to contact this group to follow up on what they have learned.
“The proposed research project will test three different treatments for lice infestations in dairy and beef heifers. This is a problem with livestock in the winter, especially pubescent and young adult animals. The usual treatment for organic farmers is to wait until the animals can go out in the spring sun and the condition clears up. But when the condition is more pronounced it can cause reduced weight gain and irritation to the animal’s skin to say nothing of their increased stress level. This increase in stress can be debilitating, leading to other health problems. At the last Animal Health Study Group meeting we had, lice was listed as one of winter’s problems. Also whenever I visit livestock farmers in the winter this problem is expressed. The producers requested a study of some treatments for lice that would be permitted in a certified organic system. The proposed study will compare three treatments and a control. The treatments include a homeopathic remedy (30c Stapysagria), a powder of four parts neem and one part turmeric, and Pyganic, a commercial product that recently became labeled for livestock treatment. Each farmer will also keep at least two control animals. Treatments will be given weekly and repeated three times after the lice infestation is recognized in the winter of 2004-2005. Results will be tabulated in the next week. If there are no positive responses from the treatment, then the protocol will be repeated.”
1) Fanatico, A. 1996. Alternative Fly Control. Butte, MT: National Center for Appropriate Technology. (out of print)
2) Macey, Anne, Ed. Canadian Organic Growers, Inc. 2000. Organic Livestock Handbook, Fly and Rodent Control chapter, pages 50-63.
3) University of Nebraska at Lincoln, Dairy Cattle Insect Management: Fly Control and Cattle Lice sections.
Note: This site provides photographs and descriptions of over 100 biological control (or biocontrol) agents of insect, disease, and weed pests in North America. It is also a tutorial on the concept and practice of biological control and integrated pest management (IPM). Excellent photos and lifecycle descriptions.
5) Organic Valley Co-op. Controlling external parasites on the organic farm.
6) Farmer Research in the Northeast. Faciliator: Diane Schivera. Organic Lice Control for Heifers
7) Dr. H.J. Karreman, DMV. January 2002 Newsletter. Penn Dutch Cow Care
8) Dr. Hubert J. Karreman, VMD. Treating Dairy Cows Naturally.
9) Paul Dettloff, DVM. Alternative Treatments for Ruminant Animals
10) Little, V.A. 1963. General and Applies Entomology. Harper and Row Publishers.
11) Organic Materials Review Institute (OMRI). June 2004. OMRI Generic Materials List, under Livestock Production Materials: enzymes.
12) Those Pesky Lice! By Cheryl K. Smith. Dairy Goat Journal May/June 2005
13) UC IPM Online. April 2004. Pests of Homes, Structures, People and Pets: Flies
14) Integrated Pest Management for Fly Control in Maine Dairy Barns. University of Maine Cooperative Extension Bulletin #5002.
15) Integrated Management of Flies in and around Dairy and Livestock Barns, DAIRY MANAGEMENT Pest Management Fact Sheet, 6/1994.
16) Make Your Own Fly Trap
Horse Talk New Mexico Horse Directory
17) David Shetlar, PhD. The Ohio State University, photos of Old Fly Traps.
18) West Virginia University Extension Service. October 1995. Stable Fly Biology and Management.
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