If you have livestock on your homestead, let's face it: you also have flies. Flies adore animal poop. It offers the perfect environment for them to lay their eggs - plus it gives both larvae and adult flies food. But flies can reduce the health and abundance on your homestead, so it's important to keep the fly population down. Your animals, your neighbors, and your family will thank you if you do.

The Life Cycle of a Fly 

If a pair of common house flies were able to live without threat, in just five months they'd have enough children to cover the entire earth...to a depth of almost 30 feet! (Source.)

Thank goodness flies have too many predators to make that actually happen, but it does prove the point that flies reproduce rapidly. Give the average house fly a moist, warm environment, along with a good supply of food, and it will go from egg to adult in only a week. It will live just 15 - 25 days, but females lay up to 500 eggs during that short lifetime. 

Other types of flies are prolific, too. Horn flies, for example, start mating 3 - 5 days after birth and females lay up to 200 eggs during their lifespan. Horse flies are similarly prolific, as are virtually every other type of fly found in the U.S. 

Life cycle of the housefly. Courtesy of Clemson University.

Not Just a Nuisance 

Unfortunately, flies aren't a mere annoyance; they can zap the abundance out of a homestead. To see just how much they can zap from us, let's take a look at the commercial livestock industry, where all the studies on this are conducted.

For example, studies conducted in the U.S. and Canada show that large numbers of flies decrease the profitability - by over $1.5 billion in the United States alone - of commercial cattle raising. Dairy cows who are pestered by flies produce up to 30% less milk. Beef cattle inflicted with flies show weight gain loss. (According to Dave Boxler, an entomologist with the University of Nebraska-Lincoln Extension office, calves whose mothers had protection against horn flies gained an average of 10 - 20 pounds more than calves whose mothers did not have protection.) 

In addition, flies are suspected to spread more than 65 different diseases to humans, as well as spreading diseases to livestock, including mastitis and other infections. Ugh!

Keeping Things Tidy 

The number one thing any of us can do to reduce the fly population on our homesteads is to avoid creating the perfect breeding ground for flies. That means, in a word: tidiness.

#1. Keep cages, pastures, and animal shelters manure-free. Flies especially love damp manure.

Keep manure cleaned up and store it away from animals.

#2. Use sawdust as a bedding, when appropriate for the animal. Sawdust is less likely to create the damp environment flies love and need. 

#3. Keep compost piles hot. Hot heaps kill the life in fly eggs. Another option is to use enclosed compost bins.

#4. Keep both manure and compost piles far away from livestock. 

#5. Understand that anywhere you allow vegetation to decay, flies will appear and reproduce. Scope out your homestead; are you leaving old plants or produce in the chicken run? (Try instead to only giving the chickens what they can reasonably eat in an hour.) Do you have spoiled hay laying around? (Compost it.) Is there any organic bedding near livestock waterers? (Compost it.) Do you have leaking or dripping water sources? (Fix 'em!)

#6. Before storage, rinse off any tools used around feed or manure, including shovels, buckets, and wheelbarrows. 

#7. If you topdress your garden or fields with manure, spread it thinly. This makes it dry out quickly, becoming inhospitable to flies and their eggs. 

Natural, Integrated Pest Management 

In addition to being tidy, it's important to let nature work for you. For example, you could buy parasitic wasps online or at farm stores. These lay their eggs on or in fly pupae, never allowing the flies to hatch. (IMPORTANT: They are not the larger type of wasps that sting humans.)

Ideally, you'll implement parasitic wasps before your fly problem gets out of control. Generally, you'll need about 500 wasps per large animal, like a cow or horse; 250 per medium animal, like a sheep or goat; and 5 per small animal, like a rabbits or chicken. If your fly population is quite large, you may need to bring in new parasitic wasps each month. Unfortunately, the cost of parasitic wasps to the average homesteader is probably on the higher side of things.

Happily, however, another natural predator to flies is one you probably already have: Wild birds, especially swallows, flycatchers, wrens, and warblers. You can encourage a healthy wild bird population on your homestead by making sure they have access to cover (in the form of shrubs, hedges, and trees - especially if they are native plants) and water sources. Spiders are also your ally in the war against flies, so don't kill them indiscriminately. That means avoiding insecticides and allowing spiders to live as undisturbed as possible - if not in your house, then elsewhere on your homestead. 

Barn swallows eat many flies. Courtesy of Michael Gäbler.

Other Natural Methods 

Flypaper may not be pretty to look at, but it's still one of the most effective and inexpensive ways to kill adult flies. Paper works by attracting flies through scent - one that typically isn't offensive to humans; when a fly lands on the sticky paper, it can't fly away and eventually dies. 

Store-bought or homemade fly traps are even more effective. These consist of a container filled with fly bait. There is only a small entrance for flies to get into the trap and no easy way for the flies to get out. Unlike flypaper, these traps are really stinky, so while they are great for outdoor use, you won't want to use them in your house. Here are the flytraps we use on our homestead - although we are considering switching to reusable ones, like these. If your trap doesn't come with bait, good choices include raw meat scraps, overripe fruit, and fresh animal manure.

In addition, when sprinkled over manure, food-grade diatomaceous earth helps dry out manure, which in turn makes it less appealing to flies. If flies lay eggs in the manure anyway, the diatomaceous earth will dry out their eggs so they don't hatch. Just be careful sprinkling it around, since it can cause respiratory problems in both livestock and humans. (Wear a mask while applying it and keep livestock and pets well away until the dust has settled.) 

It may also be possible to deter flies from problematic areas of your homestead by growing certain plants around areas of high interest, such as manure piles. Mint, lavender, and rosemary are said to repel flies. 

Mint may repel flies. Courtesy of Georgfotoart.

Some people swear by fly sprays. The type you buy are usually insecticide-based, but there are homemade versions that are all-natural and focused on plants that naturally repel flies. They are typically sprayed right on the animal - especially before milking; just be careful not to get the spray in the animals' eyes, nose, or mouth. Try this recipe: 

4 cups raw apple cider vinegar 

20 drops rosemary essential oil 

20 drops basil essential oil 

20 drops peppermint essential oil 

2 tablespoons cooking or mineral oil 

1 tablespoon dish soap 

Pour the ingredients into a spray bottle. Shake well. Shake before each application. 

DIY fly spray.

Gut buckets are another natural way to reduce the fly population. Any time you butcher an animal or have fish or other raw meat scraps, put them in a bucket that has a snap-on lid. Snap the lid part of the way down, leaving a little bit of the lid unsnapped so flies can get in and lay eggs. Let the bucket sit like this for a couple of days, then snap the lid entirely closed. In about another 3 days, the heat in the bucket will have killed both the eggs and the adult flies. Pop open the lid and repeat the process. This method works best during hot weather and when set out in full sun. Be forewarned: It will be stinky!

Using Chemicals - Wisely 

Insecticides kill beneficial insects and disrupts the natural balance of nature, so I highly recommend using all-natural methods. That said, sometimes careful use of chemicals can bring fly numbers down to a more manageable level, at which point you can convert to all natural methods. For example, you can buy larvicides that can be applied directly to manure piles. These work by preventing larvae development. If you have beef cattle, you can also try insecticidal ear tags which work simply by repelling flies away from the livestock's face. (Insecticidal ear tags are not suitable for dairy animals.) 

By being smarter than the flies - and especially by making it difficult for flies to reproduce - any homesteader can greatly reduce the fly population on their land, thereby creating a healthier, happier, and more prolific place for both animals and humans. 

Cover photo courtesy of NY State IPM Program at Cornell University. 

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