Flies in a chicken coop come from manure and wet bedding — remove those and the flies leave
Flies breed in chicken manure and damp litter. If you clean the coop regularly, replace wet bedding, and let droppings dry out, you solve the problem at the source. Most backyard keepers find that a twice-weekly cleanout of the droppings board and fresh bedding stops flies before they become a swarm. The flies you see are usually just the ones that got in before you started; once the breeding ground is gone, they die off within a week or two.
If you already have a heavy fly problem, you will need to do both: clean aggressively for the next two weeks, and use a secondary method to kill the adults while you work. Doing only one — cleaning without killing flies, or killing flies without removing manure — leaves you fighting the same battle next month.
Key Takeaways
- Remove manure and wet bedding twice a week; flies cannot breed without them, and this alone stops most infestations.
- Spread diatomaceous earth (food-grade only) on the floor and in nesting boxes to kill fly larvae and adult flies on contact.
- Hang sticky traps or fly strips inside the coop to catch adults while you clean; replace them weekly.
- Add a droppings board under roosts so manure collects in one place and dries quickly instead of mixing with bedding.
- Improve ventilation and drainage so bedding dries faster; wet litter is the single biggest fly attractant.
Clean the coop twice a week to remove fly breeding sites
Flies lay eggs in fresh manure and wet bedding. The eggs hatch in one to two days, and larvae are ready to pupate within five to seven days. If you remove manure before eggs hatch, you break the cycle. A twice-weekly cleanout is the most reliable method because it fits most backyard schedules and still stays ahead of the fly life cycle.
Focus on the droppings board under the roosts first — this is where the most manure collects overnight. Scrape it clean and replace the bedding underneath. Then walk the coop floor and remove any clumped, wet litter. Leave dry bedding in place. If the whole floor is damp, replace all of it; wet bedding is a fly nursery. Pile the old manure and bedding in a compost bin or covered container away from the coop, not in an open heap where flies will breed in it and fly back to your birds.
Use food-grade diatomaceous earth on floors and in nesting boxes
Food-grade diatomaceous earth (DE) is a powder made from fossilized algae. It kills insects by damaging their outer shell, causing them to dry out. Dust it on the coop floor, under bedding, and in nesting boxes where flies hide. It works on both larvae and adults. Do not use pool-grade DE — it is treated with chemicals and is toxic to birds.
Spread a thin layer (about one-quarter inch) across the floor and mix it into the top layer of bedding. Reapply after you clean the coop and add fresh bedding, and again after rain or when the powder gets damp. DE loses its killing power when wet. Wear a dust mask when explore it so you do not inhale the powder. The birds will not be harmed by walking through it or pecking at it, but you should not let them breathe heavy dust clouds either.
DE works slowly — it takes three to five days to kill a population — so combine it with other methods for faster results. It is most useful as a maintenance tool after you have already reduced the fly population through cleaning.
Hang sticky traps and fly strips to catch adults
Sticky traps and fly strips catch adult flies before they lay eggs. Hang them inside the coop, away from where the birds roost (so they do not stick to feathers). Place them near the door, in corners, and along walls where flies tend to rest. Replace them weekly or when they are covered with flies.
Sticky traps work best when the coop is already cleaner than it was — they catch flies that are still around, but they do not stop new flies from breeding in manure. Use them alongside cleaning and DE, not instead of cleaning. A single trap will not solve a heavy infestation, but three or four traps in a medium coop will noticeably reduce the adult population while you work on removing breeding sites.
Add a droppings board under roosts to contain manure
A droppings board is a flat surface (plywood, metal, or plastic) installed directly under the roost bars. Chickens drop most of their manure at night while roosting, so the board catches it all in one place instead of letting it mix with bedding on the floor. This makes cleaning faster and keeps manure from staying damp in the litter.
Install the board about 12 to 18 inches below the roost bars, high enough that you can slide a scraper underneath. Scrape it clean every morning or every other morning, and the manure will dry quickly in the air. If you leave it for more than a day, it gets damp and flies will breed in it. A droppings board is one of the single best fly-prevention tools because it removes the largest source of manure from contact with bedding.
Improve ventilation and drainage so bedding dries faster
Wet bedding is the main reason flies thrive in a coop. If air does not move through the coop, moisture stays trapped and bedding stays damp even after you add fresh litter. Check that your coop has vents on opposite sides (so air flows through, not just in one direction). Vents should be covered with hardware cloth to keep predators out, but they should not be blocked by feeders, waterers, or stored items.
Make sure water does not pool on the floor. If your waterer leaks or spills, it will soak the bedding. Use a waterer with a drip tray underneath, or place it on a wire platform so spilled water drains away instead of soaking into litter. If the coop sits on wet ground, add drainage around the outside — a shallow trench or gravel bed will help water run away from the coop instead of seeping through the floor.
Use fly bait or spray only as a last resort
Fly baits and sprays kill adults quickly, but they are not a substitute for cleaning. Most fly baits sold for coops are safe for birds when used as directed, but they work best on a coop that is already cleaner than average. If you use bait or spray without removing manure and wet bedding, you will kill the flies you see today and have a new population in a week.
If you choose to use a spray or bait, read the label carefully to confirm it is safe for poultry and food-producing animals. Follow the dosage exactly. Keep birds away from the treated area for the time stated on the label. Spray or bait in the evening when birds are roosting, and ventilate the coop well before they return to it in the morning.
Frequently Asked Questions
Can I use regular diatomaceous earth from a garden store?
No. Pool-grade diatomaceous earth is treated with chemicals and will poison your birds. Buy only food-grade DE, which is labeled as safe for use around animals and food. It costs a little more but is the only safe choice for a chicken coop.
How long does it take to get rid of flies if I clean regularly?
If you remove manure and wet bedding twice a week, you should see a noticeable drop in flies within one to two weeks. The flies you see are mostly adults that hatched before you started cleaning; once the breeding sites are gone, they die off naturally. Heavy infestations may take three to four weeks to clear.
Will my chickens get sick from flies?
Flies themselves do not usually make chickens sick, but they are attracted to manure and can carry bacteria. A heavy fly population is a sign that the coop is too wet or dirty, which can lead to respiratory problems or parasites. Cleaning regularly protects your birds' health by keeping the coop dry and sanitary.
Do I need to treat the area outside the coop too?
If you compost manure in a bin or covered container, you do not need to treat it. If manure sits in an open pile, flies will breed in it and fly back to the coop. Move compost away from the coop, cover it, or turn it regularly so it heats up and kills fly larvae.
What if I only have a few flies — do I still need to clean twice a week?
Once-weekly cleaning may be enough if your coop is small and you have good ventilation and drainage. But if flies start to appear, move to twice-weekly cleaning when ready. Waiting until you have a swarm makes the problem much harder to solve. A few flies now means breeding is already happening.