Mosquitoes might be just a buzz-and-bite nuisance for you and your family, but they can harm the cattle on your farm. Mosquitoes harm cattle by injecting viruses and spreading diseases, causing skin lesions, allergic reactions, and weight loss. After a natural disaster, mosquitoes swarm and can cause a lack of oxygen intake, blood loss, and exhaustion in animals already disoriented by the disaster.
How can you protect your cattle from mosquitoes? The best way to protect cattle from mosquitoes is to eliminate the mosquito’s breeding ground—standing water. Whether you want to protect your hundred-cow herd or your child’s 4-H calf, your best bet is to drain standing water around the farm and remove fixtures that hold water. This can diminish the hatching areas around your cattle and prevent further mosquito outbreaks.
The techniques in eradicating mosquitoes differ per stage in the mosquito’s development. To prevent mosquitoes from hatching in the first place, we’ll look at how to remove standing water, a mosquito’s hatching habitat. Then, we’ll consider some of the effective and not-so-effective mechanical and chemical (including natural) techniques used to reduce mosquito populations after they hatch.
The Mosquito’s Life Cycle: The Key To Effective Elimination
To make your mosquito-elimination plan most effective, understand that the mosquito’s life cycle moves from egg to larvae to pupa to adult in about eight to 10 days or two to five weeks, depending on the variety of mosquitoes, climate, and weather conditions, including temperature. Before laying eggs, females feast on blood to mature those eggs. (Males feed on nectar, do not bite, and do not draw blood.)
Females lay their eggs—100 at a time—in standing water. These eggs need to be submerged in water but can survive without water for up to eight months. Most adult mosquitoes stay within 300 feet from where they’ve hatched, although their territory could range up to a mile and farther. Adult mosquitoes can live for two to three weeks.
1. Remove Standing Water
Your top priority should be removing standing water around your farm buildings and in surrounding fields and pastures to prevent mosquitoes from hatching in the first place. How you lessen wet spots depends on the situation. Caution: Before you start to drain large tracts of land, swamps, or areas near a stream, check out the wetland regulations for your area.
Areas That Collect Standing Water And Breeding Mosquitoes
- Larger fields—Removing water from a large field might happen best underground. This would involve installing subsurface drain tile, which will require someone who knows what they’re doing. Installing tile means operating backhoe equipment to dig a narrow ditch, adding a base layer of stone, installing the drain tile, adding more stone, backfilling the trench, and reseeding the pasture or field. Draining water away underground prevents it from surfacing in the first place.
- Wetlands—During the drier months, mow any wetlands to reduce tall grasses, rushes, and cattails. Again, contact your local conservation district or governing authority for local wetland regulations.
- Ponds—Ponds can become an excellent ending place for your standing field and pasture water. If you have a pond on your property or want to build one, keep these suggestions in mind.
Steps to Reduce Mosquitoes Around Ponds
You can take many steps to reduce mosquitoes around ponds. Just because you have a pond doesn’t mean you have to give up controlling mosquitoes.
- Reshape or build ponds with steeper edges to reduce shallow water, which is prime mosquito-breeding habitat.
- Keep algae to a minimum because algae are an excellent source of food for hatching mosquito larvae. Excessive nitrogen and phosphorus from adjoining fields can cause algae to grow beyond what’s healthy for other pond life, including fish. While algae usually aren’t dangerous, blue-green algae can be toxic to livestock.
- Avoid using chemical insecticides since they kill beneficial insects, too. Bacterial insecticides won’t harm other wildlife.
- Consider adding mosquito-eating fish. These can include koi carp, minnows, guppies, and, how convenient, mosquitofish (Gambusia affinis) can eat between 100 to 500 mosquito larvae each day. But, check with your local fish and game commission for the best kinds of fish for your area and for any regulations you’ll need to follow.
- Get rid of pondweeds by manually raking and composting the weeds. Or, rid your pond of weeds using herbicides. First, identify the weeds. Depending on the type of weed or grass, you may be able to apply some herbicides yourself, but for others, you’ll need a professional who is certified to apply the herbicides. Also, if appropriate for your area and climate, you can add grass carp to your pond to feed on aquatic weeds. To keep pond weeds and grasses from growing, refrain from feeding ducks and geese, add a water aerator, and avoid using too much fertilizer in fields and banks around the pond.
- Wet spots—Leveling out or refilling a wet spot in a field or pasture can hasten water evaporation. Strategically placed ditches can move the water away from the wet spot to a lower area.
- Watering troughs and rainwater collection tanks—If you’re collecting rainwater or filling watering troughs with rainwater directly from a building’s downspout, all inflow and outlet pipes should be covered with mosquito-proof screens and flap valves. Screens and valves should be made from brass, copper, aluminum, or stainless steel to prevent rusting or corroding. Check often for torn screens. Every couple of months, check, clean, and flush your rain-collection system. Clean the tank at the same time. If you’ve installed a specialized rain-collection system, call a professional to maintain and clean the system.
- Feeding racks and troughs—Wet areas often develop around metal hay racks or feed troughs where cattle congregate to eat hay or grain. Move these feeders often so that wet spots can dry naturally, and move them during dry weather to prevent ruts from your vehicle’s tires. Water will pool in the ruts and attract mosquitoes.
- Rotational grazing—Rotate cattle in separate pastures so that wet spots and whole fields can dry out. Use temporary fencing to keep cattle in drier areas.
- Pasturing cattle—Don’t pasture cattle in soft pastures. Their hoof prints can become mini ponds for standing water. Choose higher, drier, more well-drained areas to pasture cattle.
- Managing your farm’s wastewater—Take time to observe surface runoffs and erosion in your fields and pastures. Where does it stagnate? On production farms, wastewater can come from wash water from milking parlors, egg washing, slaughterhouses, and composting areas. Consult USDA resources for your specific wastewater solution.
- Keep containers clean—Around farm buildings and cattle housing, keep troughs and bowls clean. Unclog gutters and drains, and keep gutters, birdbaths, and pet food bowls clean.
- Remove trash—Remove old tires, containers, lids, and trash that can hold water, especially after a rain. Plan to take a walk out around your farm buildings after rain to identify rain collectors.
- Fill in potholes—Check your farm lanes and driveways for potholes, washes, and erosion ditches. Fill potholes often, especially during rainy and mosquito-breeding seasons.
- Manage stormwater and rainwater—Make sure that any stormwater or rainwater gushing off your buildings’ roofs and downspouts drains away from the buildings effectively and does not pool. If water does pool at the end of the rain spout, consider adding plants that will absorb extra water. The roots will help percolate the soil, too. An enclosed cistern or rain barrel can catch extra water, which is used in gardens or flowerbeds. If rainwater pools on bare ground, planting ground covers can help reduce erosion and prevent standing water where mosquitoes can lay eggs.
- Check for natural water traps, such as old tree stumps with hollow centers and places where rotten foliage piles up. Walk your pastures, fields, and fencerows after rain to find soggy spots that aren’t draining.
Mechanical Methods To Keep Mosquitoes Away From Cattle
Listed here are the more effective methods of protecting cattle from mosquitoes.
- Water aerators—Mosquitoes can’t reproduce in moving water, so consider setting up some pumps or fountains in your ponds and watering troughs. Disrupting the water can disrupt the breeding habitat of mosquitoes and make being there less enticing.
- Fans—Installing fans in cattle loafing areas helps to shoo away mosquitoes in two ways. First, mosquitoes aren’t excellent fliers. They don’t like wind currents faster than five to 10 miles per hour or faster. So, they’ll avoid areas—and the cattle in those areas—where they can’t fly or land safely. Second, mosquitoes are attracted to carbon dioxide and tend to fly, in a zigzag fashion, directly to those pockets of carbon dioxide exhaled by cattle and humans. Install fans in cattle housing to help to disperse this invisible gas and to keep wind currents going.
- Aerial spraying—This mosquito-control method belongs to local governments and mosquito-control districts. They monitor mosquito populations and the spread of diseases and decide when to spray. Aerial spraying may target larvae or adult mosquitoes. Low-flying planes distribute the proper insecticide around dusk or early morning. Local newspapers and radio stations will announce the dates and times of spraying.
You can use some of the following less-effective methods of eliminating or reducing mosquitoes around your cattle in conjunction with other means. With some methods listed here, it’s best to save your money.
- Bug zappers—Tests conducted daily show that only four to six percent were mosquitoes of the insects eliminated. Unfortunately, of the other insects destroyed by bug zappers, many were beneficial.
- Lighting—Check the kind of lighting in your barn and loafing pens. Yellow incandescent or fluorescent lights are reported to be less attractive to mosquitoes.
- Ultrasonic devices—Studies show that mosquitoes are not affected by ultrasound, so it’s best to save your money.
- Mosquito traps—Sticky strips and electric grids do work, but their effectiveness depends on several factors, such as the mosquito population size. Some traps attract mosquitoes by emitting carbon dioxide, along with other natural mosquito attractants. These devices require regular maintenance, too, like replacing insect strips. Remember: Mosquito traps are designed to attract mosquitoes, so placement around cattle is critical.
- Bats—Bats eat more moths, beetles, and wasps than mosquitoes, so this method is less reliable. But because bats need your help due to their own faltering populations, it would be a kind gesture to put up a bat house anyway.
- Dragonflies—Dragonfly nymphs eat mosquito larvae, and adult dragonflies eat adult mosquitoes. Some sources suggest adding dragonfly nymphs to ponds.
- Purple martins—While dragonflies prey on mosquitoes, purple martins prey on dragonflies. Keep in mind that birds, in general, nest at night when mosquitoes are most active.
Chemical Methods to Keep Mosquitoes Away From Cows
- Repellents—According to Parasitipedia.net, a natural or chemical repellent “…must reach the approaching parasite before it lands or otherwise gets in contact with its host. To achieve this, the compound must necessarily be volatile, i.e., applied on the host (directly or in devices such as collars or ear-tags impregnated with it), it must evaporate enough to build a cloud around it that, once perceived by the parasite, it will discourage it from making contact with the host.”
Because this cloud will eventually evaporate, usually within a few hours or a day, repellents become ineffective—and too expensive—for more than a few cattle. They may give temporary relief to a show cow, but be sure to use only cattle-approved repellents. Pour-on products tend to be more effective than sprays or dips. Read the label or contact your veterinarian.
Synthetic repellents include DEET, pyrethroids, and icaridin, picaridin, or hepidanin.
Natural repellents include pyrethrins, nepetalactone, menthoglycol, citronella oil, neem oil, and myrica gale essential oil.
- Ear tags—Most insecticides in ear tags target flies, not mosquitoes. Check the packaging details and instructions to see if they’d benefit one animal, such as a 4-H calf, heifer, or cow.
- Vaccines—No vaccines have been developed to protect livestock against mosquitoes.
- Foggers—To be effective, mosquitoes must come into contact with the fog that’s being discharged. The insecticide in the fog kills the insects. The effects of fogging last up to three days, depending on the brand of fogger. Foggers are also fire and explosion hazards if used near an open flame. And, people with asthma should avoid the area.
- Larvicides—According to the CDC, larvicides are “…a type of insecticide used to control mosquitoes indoors and outdoors around your home. They work by killing mosquito larvae before they can grow into adults. Some formulations are activated when ingested by the mosquitoes, and some formulations work when they come into contact with the larvae. When used according to product label instructions, larvicides do not harm people, pets, or the environment.”
Two types of larvicides exist Liquids sprayed from backpacks, trucks, or airplanes and “dunks, tablets, baits, pellets, granules, and briquettes” added to mosquito-breeding areas.
Use only EPA-approved products and ones that target the appropriate stage of mosquito development.
- SIT—Although SIT isn’t a do-it-yourself-on-the-farm technology, SIT does offer hope down the road. According to mosquito.org, SIT is “…the release of altered male mosquitoes that cause the production of no offspring or produce offspring that will not survive to the adult stage when they mate with local female mosquitoes in the wild.”
- Biopesticides—Scientists at USDA’s Agricultural Research Service are “…evaluating fungi and bacteria that already exist in nature and turning these mosquito-killing microbes into biopesticides that target mosquito eggs, larvae, and adults. The process is similar to combatting invasive plants by importing natural enemies from their homelands. Researchers identify beneficial microbes, test them for specificity against a target pest, then develop large-scale production for release against the pest.”
ARS scientist Jose Ramirez reports that “Non-chemical strategies allow farmers to practice pest control over vast areas without environmental contamination and the detrimental effects on beneficial insects, such as pollinators, that are important for crop production.”
Frequently Asked Questions
Can mosquitoes kill a cow? Mosquitoes disrupted by a hurricane can swarm and kill livestock. Most recently, Hurricane Laura left behind mosquitoes that killed an estimated 400 heads of livestock. Hurricanes have traditionally caused increased issues with mosquitoes that have left hundreds of cows dead. Mosquito swarming has happened in Louisiana after hurricanes Laura in 2020, Rita in 2005, and Lili in 2002. The issue of dead livestock from mosquitoes is likely more widespread than thought because of the additional toll that hurricanes take on an area.
How can I protect pets from mosquitoes? When purchasing bug sprays for pets, read the label to see if the spray protects against mosquitoes. Not all do. Monthly repellents you apply to your pet’s back may work against mosquitoes, too. Again, read the label. Some repellents that work for dogs are toxic to cats. When considering natural repellents, ensure that they’re meant for specific pets.