LIVESTOCK NUTRITION SUPPLIES

June Edition

Fighting Flies, Ticks, Mosquitoes & More

The Case for All-Natural, Multi-Layer Protection

For Cattle, Horses, Sheep, Goats & All Livestock

Summer brings green grass, longer days — and an onslaught of ectoparasites. Flies, ticks, and mosquitoes are not merely a nuisance. They are a direct tax on your operation’s productivity, costing the U.S. beef industry an estimated $2.2 billion per year in lost performance and treatment costs. And in the summer of 2025, a new and more serious threat has re-emerged on U.S. soil for the first time in decades.

At Livestock Nutrition Supplies, we hear from producers who have relied on conventional chemical treatments for years and are frustrated with diminishing returns, resistance problems, and growing concerns about residues and withdrawal times. The good news: a well-designed, all-natural Integrated Pest Management (IPM) program can be just as effective — and in most cases more sustainable — as a chemical-dependent approach. This newsletter lays out the full threat landscape and a practical framework for protecting every animal on your operation naturally.

Know Your Enemy: The Full Threat Landscape

Horn Flies & Face Flies

Horn flies (Haematobia irritans) are the most economically damaging pest of pasture cattle in North America. A single cow may carry 200 to 4,000 horn flies at any given time, with each female feeding up to 30 times per day. Research consistently shows horn fly populations above 200 per animal cause measurable losses in average daily gain, ranging from 15 to 50 pounds per animal per season — directly cutting into profitability at sale.

Face flies (Musca autumnalis) cluster around eyes, nostrils, and wounds — spreading infectious bovine keratoconjunctivitis (IBK), more commonly known as pinkeye. A single pinkeye case can cost $150 to $300 in treatment, reduced gain, and potential calf death loss. Face flies are also a critical concern in the context of New World Screwworm: face flies visit open wounds and mucous membranes, which are the same sites NWS flies target for egg-laying. Reducing face fly pressure reduces the overall fly activity around vulnerable wound sites on your animals.

Horses and ponies are highly susceptible to stable flies and face flies, which cause agitation, interrupted grazing, and weight loss. In dairy operations, fly pressure directly reduces milk production through stress responses and teat irritation.

New World Screwworm (Cochliomyia hominivorax)

New World Screwworm is categorically different from every other pest discussed in this newsletter. Where horn flies, face flies, and stable flies feed on blood or secretions, NWS larvae (maggots) invade and consume the living tissue of warm-blooded animals. Once eggs hatch in a wound or body opening, larvae burrow deeper using sharp mouth hooks — the "screwing" motion that gives the fly its name — feeding on living flesh as they go. Without treatment, an infested animal can die within one week.

The NWS fly (Cochliomyia hominivorax) was eradicated from the United States in 1966 through a landmark sterile insect technique (SIT) program — one of the greatest achievements in American agricultural history. Since 2023, however, the parasite has been re-emerging northward through Central America and Mexico, and on June 3, 2026, USDA-APHIS confirmed the first U.S. livestock case in Zavala County, Texas.

Every species of warm-blooded animal is susceptible: beef cattle, dairy cattle, horses, sheep, goats, hogs, dogs, cats, and in rare cases, people. Animals at the highest risk include:

•       Newborns with fresh umbilical cords (the umbilical area is a primary NWS oviposition site)

•       Animals with any open wound, including post-dehorning, branding, castration, ear notching, or tail docking sites

•       Animals with tick wounds, fight wounds, barbed wire injuries, or foot rot

•       Females post-parturition with birth canal or udder injuries

•       Animals with pinkeye lesions or other mucous membrane irritation

The economic stakes are enormous. Before eradication, NWS cost U.S. cattle producers hundreds of millions of dollars annually. A re-establishment of NWS in the southern United States would affect not only affected operations but the entire domestic livestock market, supply chains, and export eligibility.

Ticks

Multiple tick species affect livestock across the Plains and Midwest, including the lone star tick, the American dog tick, and the Gulf Coast tick. Ticks transmit anaplasmosis, theileriosis, and Rocky Mountain spotted fever. In cattle, a heavy anaplasmosis outbreak can result in mortality rates of 30 to 50 percent in unvaccinated, highly susceptible animals.

Ticks also have a direct connection to NWS risk: tick bite wounds create exactly the kind of small, open skin lesions that NWS flies can exploit for egg-laying. Controlling tick burden on your livestock is not just about anaplasmosis prevention — in 2025 and beyond, it is also a frontline defense against screwworm infestation.

Sheep and goats face intense tick burden risk as well, with ticks capable of causing tick paralysis in young lambs and kids. Horses suffer from tick-borne conditions including equine piroplasmosis and Lyme disease.

Mosquitoes

Mosquitoes are vectors for Epizootic Hemorrhagic Disease (EHD), bluetongue virus, and West Nile virus. EHD primarily devastates white-tailed deer populations, but cattle and sheep can be affected in endemic areas. West Nile virus is a serious and potentially fatal threat to horses. Beyond disease transmission, mosquito pressure alters behavior across all livestock species, reducing grazing time, feed efficiency, and average daily gain.

Why Chemical-Only Programs Break Down

For decades, the default response to ectoparasite pressure has been synthetic insecticides: pyrethroid pour-ons, organophosphate ear tags, and synthetic spray programs. Used as a sole defense, they set the stage for failure in three predictable ways.

1. Resistance Development

Pesticide resistance is not a future risk — it is a present reality. Pyrethroid resistance in horn fly populations has been confirmed across the United States, including throughout Nebraska and surrounding states. Some local populations now carry resistance to multiple insecticide classes simultaneously. With horn flies completing a full life cycle in as little as 10 to 14 days during summer, a resistant population can dominate your pastures within a single season.

2. Sub-Lethal Exposure Accelerates Resistance

Leaving insecticide ear tags on cattle past the end of fly season, or allowing pour-ons to weather down to sub-lethal concentrations, is arguably more damaging than no treatment in terms of resistance selection. Flies exposed to doses that do not kill them are the most likely to survive, reproduce, and produce resistant offspring.

3. Residue, Withdrawal & Market Concerns

Chemical ectoparasite controls carry withdrawal times that affect market eligibility for beef and dairy. Producers targeting natural, grass-finished, or certified organic markets face additional scrutiny. Export markets with strict residue standards also create strong economic incentives to minimize or eliminate synthetic chemical use.

Building Your All-Natural IPM Program

Integrated Pest Management (IPM) means using multiple tools with different modes of action to control pest populations from several angles simultaneously. When your tools are all natural, the benefits compound: no resistance development, no withdrawal concerns, no chemical residues, and a program that grows more effective over time.

Natural Ectoparasite Control Reference Guide

* In NWS-endemic or risk areas, consult your veterinarian before scheduling dehorning, branding, castration, or other wound-creating procedures. If procedures must be performed, treat resulting wounds immediately with appropriate products and monitor closely.

Layer 1: Environmental & Habitat Management

The most powerful and least expensive layer of any IPM program is habitat management. Remove the environment pests need to breed, and you reduce populations before they ever reach your animals.

•       Manure management is the single most impactful horn fly and stable fly control measure available. Horn fly larvae only develop in undisturbed cattle manure deposited on pasture. Frequent spreading disrupts the breeding cycle significantly.

•       Eliminate standing water wherever possible to reduce mosquito breeding. Even small volumes accumulating in shaded areas can support substantial mosquito populations within days.

•       Rotational grazing moves livestock away from heavily contaminated pastures, breaking the pest’s habitat and host-finding cycle simultaneously. This practice benefits forage utilization, soil health, and parasite management across all livestock species.

•       Manage brush and tall grass around handling facilities, shade structures, and water sources to reduce tick habitat.

•       Ventilation in barns and stables reduces stable fly, house fly, and gnat pressure. Fans create air movement that disrupts insect flight behavior.

•       Minimize open wounds whenever possible. Barbed wire hazards, sharp equipment, and rough handling that causes skin abrasion all create NWS oviposition opportunities. Inspect fencing and facilities regularly. Every wound on every animal is a potential entry point.

Layer 2: Wound Care — Your Most Critical NWS Defense

In the context of New World Screwworm, wound care is not optional — it is a biosecurity imperative. NWS flies are attracted to fresh wounds, birth fluids, and mucous membranes. A clean, covered wound does not attract screwworm flies. A neglected, open wound is an invitation.

Natural wound care practices that reduce NWS and blowfly risk:

•       Inspect all animals daily — especially newborns (umbilical area), recently processed animals, and any animal with known injuries. Early detection is the difference between a treatable case and a fatal one.

•       Clean wounds promptly and thoroughly with antiseptic solution. Remove all debris and keep wounds free from attractants.

•       Apply wound coverings or wound dressings to reduce fly access. While traditional chemical wound sprays exist, wound dressings that physically exclude flies (bandaging where practical, pine tar-based dressings) provide coverage without chemical exposure.

•       Treat umbilical cords of newborn calves, foals, lambs, and kids immediately at birth. Clean and monitor navel stumps daily until fully healed.

•       Postpone elective wound-creating procedures (dehorning, castration, branding, ear notching, shearing) when NWS risk is elevated in your region. If procedures must be performed, do so in cooler parts of the day, have wound care ready immediately, and monitor treated animals closely for 2 weeks.

•       Manage pinkeye (IBK) aggressively. Eye lesions attract face flies, and in NWS risk areas, they also represent vulnerable tissue for NWS oviposition. (See Vitamin A, D & E supplement recommendation below.)

Layer 3: Biological Controls

Biological controls work with nature rather than against it, establishing natural enemies of pest species that provide ongoing, self-sustaining pressure on fly populations.

Dung Beetles

Dung beetles are one of the most powerful and underutilized natural horn fly controls in agriculture. Their activity alone can reduce horn fly emergence by 90 percent or more in well-managed pastures. Critical note: avermectin dewormers (ivermectin, doramectin) are highly toxic to dung beetles when excreted in treated manure. Work with your veterinarian on targeted deworming schedules that protect beetle populations during summer months.

Parasitic Wasps (Fly Parasites)

Commercially available parasitic wasps such as Spalangia cameroni and Muscidifurax raptor lay their eggs inside fly pupae, killing them before adult flies emerge. These tiny, stingless wasps are harmless to all livestock and humans and are highly effective when released consistently throughout the fly season near manure accumulation areas. Most suppliers recommend bi-weekly releases from late April through September.

Layer 4: Physical & Mechanical Controls

•       Fly traps (sticky traps, baited traps, UV light traps) placed around waterers, feeders, and shade structures can capture large numbers of adult flies and reduce pressure on livestock without any chemistry.

•       Back rubbers and dust bags positioned at gates, waterers, and mineral stations allow cattle to self-treat with natural formulations such as diatomaceous earth or essential oil-based dust, leveraging existing animal behavior.

•       Screens and curtains in horse stalls, dairy barns, and sheep or goat housing reduce mosquito and gnat infiltration. Combined with fans creating outward airflow, these measures can nearly eliminate indoor insect pressure.

•       Fly masks and leg wraps for horses provide direct protection for the face and lower limbs — the most common sites for fly irritation and summer sores in equine.

Layer 5: Nutritional & Supplemental Controls

Garlic: The Cornerstone of Natural Pest Repellency

Garlic (Allium sativum) is the most well-documented natural systemic insect repellent available for livestock. When cattle, horses, sheep, or goats consume garlic, allicin and related allyl sulfide compounds are metabolized and excreted through the skin, breath, and body secretions. These volatile compounds are repellent to horn flies, face flies, stable flies, ticks, and mosquitoes.

In the context of New World Screwworm, garlic’s systemic repellency is relevant as a deterrent to adult fly attraction and approach. While garlic is not a treatment for active NWS infestation and should never be substituted for veterinary care, reducing the overall fly pressure around your animals — including the attraction of flies to wounds — is a legitimate component of a prevention-focused management strategy. Published research on garlic supplementation documents:

•       Significantly reduced horn fly and face fly counts on supplemented animals throughout the fly season

•       Reduced tick attachment in sheep supplemented with garlic-containing feeds

•       Decreased fly landing and settling behavior observed across multiple studies

•       A dose-dependent, cumulative effect — best results occur when supplementation begins 30 days before pest season and continues through first frost

Diatomaceous Earth (DE)

Food-grade diatomaceous earth is a naturally occurring silica compound that damages the waxy outer cuticle of insects, causing dehydration and death through a purely physical mechanism. Insects cannot develop resistance to physical modes of action. DE is included in LNS Complete W/ Probiotic & Garlic, and can additionally be applied topically to animal backs, flanks, and faces, or spread in loafing areas and stall bedding.

Essential Oil-Based Repellents

Neem oil, citronella, eucalyptus, clove, thyme, and cedarwood oils have demonstrated repellent activity against flies and mosquitoes. Essential oil-based repellent sprays and rubs are particularly valuable for horses, dairy cattle, and show animals where chemical residue concerns are highest. They carry no resistance risk, no withdrawal time, and are safe for use on all livestock including pregnant animals.

Layer 6: Targeted Vitamin Support for Pest-Transmitted Disease Prevention

A nutritionally complete, well-supported animal is more resistant to pest-borne disease. Specifically, adequate levels of Vitamins A, D, and E are foundational to the mucous membrane integrity and immune function that resist pest-transmitted infection — and, critically, healthy skin and mucous membranes are less attractive oviposition sites for screwworm flies.

Vitamin A is critical to ocular and mucosal health. Deficiency significantly increases susceptibility to pinkeye (IBK) transmitted by face flies. In NWS risk areas, pinkeye lesions represent vulnerable mucous membrane tissue that can attract additional fly activity. Managing IBK proactively with Vitamin A support is therefore both a disease-prevention and a screwworm-prevention strategy.

Species-Specific Considerations

Beef & Dairy Cattle

Horn fly control is the highest-ROI pest management investment for beef cattle operations. A conservative estimate of $30 to $50 in performance loss per head per season from horn fly burden means effective control pays for itself many times over. For NWS risk, focus especially on newborn calf management — the umbilical area is the most common initial NWS infestation site in calves. Treat all navels at birth, monitor daily, and establish a strong veterinary-client-patient relationship now so you have a clear action plan if NWS is detected.

Horses & Equine

Horses are among the most pest-sensitive livestock species. Stable flies cause stamping, kicking, and agitation that reduces feed efficiency. Sweet itch (insect bite hypersensitivity) affects a significant percentage of horses and is triggered primarily by Culicoides midges. For horses, a complete natural program includes garlic supplementation, essential oil-based topical repellents, physical protection (fly masks, leg wraps, sheets), barn screens and fans, and consistent manure management.

NWS risk in horses is significant: wounds from barbed wire, kicks, and tack sores are common, and the equine face and lower legs are frequent sites of summer sores (habronemiasis) that could also attract screwworm fly attention in risk areas. Inspect horses daily for any skin breakdown or wound, and treat immediately.

Sheep & Goats

Sheep are particularly vulnerable to blowfly strike (wool maggots) in summer. Crutching and maintaining clean fleece reduces risk. Goats face strong pressure from horn flies and lice during summer, and tick attachment can be severe in browse-heavy environments.

Copper warning: LNS Complete W/ Probiotic & Garlic is formulated for cattle and goats. Sheep have very low copper tolerance. Do not feed this product to sheep. Consult your nutritionist or veterinarian for a sheep-appropriate mineral formulation. LNS Vitamin A, D & E W/ 10G Probiotic is appropriate for sheep.

Hogs

Stable flies and house flies are the primary ectoparasite concerns in swine operations. The foundational control is aggressive manure management. Parasitic wasp programs and physical fly traps work well in confinement hog facilities. Garlic can be supplemented in swine feed and has shown both health and pest-repellent benefits.

Your All-Natural Ectoparasite Calendar

LNS Is Here to Work With You

At Livestock Nutrition Supplies LLC, we believe that the best livestock nutrition and pest management programs are built on science, not shortcuts. Our products are formulated with ingredients that support your animals from the inside out — and our team is available to help you think through a program that fits your operation, your species mix, and your management philosophy.

Whether you’re running stocker cattle on grass, managing a horse facility, or running a mixed-species operation, the right supplement program is a cornerstone of your pest management strategy. LNS Complete W/ Probiotic & Garlic and LNS Vitamin A, D & E W/ 10G Probiotic are two of the most practical, cost-effective tools available for natural ectoparasite defense and disease prevention.

And for ration building, nutritional analysis, and supplement planning on the go, visit us at lnas.pro — our Livestock Nutrition Analysis System is designed to help producers and nutritionists optimize herd performance from any device, anywhere.

Questions? Ready to build your summer supplement program?

Livestock Nutrition Supplies LLC  •  Crete, Nebraska

Info@LivestockNutitionSupplies.com  •  lnas.pro

livestocknutritionsupplies.com

Disclaimer:

This newsletter is provided for educational and informational purposes and reflects general industry knowledge and current publicly available information. New World Screwworm is a reportable foreign animal disease in the United States — if NWS is suspected, contact your state animal health official or USDA immediately. Do not attempt to self-diagnose or self-treat suspected NWS cases without veterinary involvement. Always consult a licensed veterinarian or livestock nutritionist before implementing changes to your animal health, pest management, or supplementation program. LNS Complete W/ Probiotic & Garlic contains added copper and should not be