Chickens get lice from other birds. A louse spends its whole life on a bird, and it doesn’t last long once it falls off. Kentucky’s extension fact sheet puts that at about a week. So lice don’t grow out of dirty bedding, and they don’t mean your coop is filthy. They ride in on a new hen or on a crate a bird traveled in. A wild bird that gets close to your flock can bring them too. Then they spread from bird to bird. Once they’re in, the hen that can’t groom well or skips her dust bath ends up carrying the most.
I rewrote this page from 12 sources, and you’ll find them all at the bottom. The core is the Merck Veterinary Manual’s chapter on poultry lice. Amy Murillo of UC Riverside wrote it, and it was last reviewed in January 2026. Next to it sit six extension guides, led by UC’s guide to lice and mites and Kentucky’s fact sheet on backyard chickens. Five published studies fill in the rest. Four come from UC Riverside’s entomology department, and one counted lice on wild turkeys. I’ll name each one as it comes up.
The old version of this page opened with a story. It was about a hen called “ol’ Henrietta” and a narrator who said “I about lost my lunch!” on finding her lice. I can’t vouch for any of it, so it’s gone. Most of its numbers went with it. It said adult lice “live 4-6 weeks” and that females lay “3-10 nits per day”. It said “nits hatch into nymphs in 10-14 days”, and UC says 4 to 7. It gave lice “piercing-sucking mouthparts”, but the vet and extension sources say they chew. It said “Population explosions tend to occur in spring and fall”, and UC says lice peak in autumn and winter. It told you to “Repeat cleaning every 2-4 weeks” and to “Rotate deworming and louse treatments every 60-90 days”. I couldn’t find a source for either one. Its timelines for isolating birds and resting a pasture had no source either, so they’re gone too. It suggested “Spray-on apple cider vinegar” and “Garlic oil solutions”. It suggested “Tea tree oil mixes” too. I couldn’t find a trial behind any of those, so they’re out. So is “Consider shearing heavily infested birds”. The 30-day quarantine for new birds stays, because Colorado State says the same thing.
A word on the photos. None of them shows a louse. I searched the free photo libraries for a real close-up of a chicken louse I could use here, and I came up empty. If you want to see what you’re hunting for, UC’s lice and mites guide (linked below) has two close photos of louse egg clusters at the base of vent feathers. Nancy Hinkle of the University of Georgia took one, and Brad Mullens of UC Riverside took the other. The two red hens up top and the white chicken come from Unsplash. Three of the photos come from a photographer in Mayenne, France, going by their Flickr profile. The caged hens were photographed by USDA at an egg farm in San Sebastián, Puerto Rico, in March 2018. The wild turkey was photographed by the US Fish and Wildlife Service in July 2019.
The short version.
- Lice live their whole life on a bird and die within about a week off it. They come in on another bird or the crate it rode in.
- Check the skin around the vent and under the wings, in daylight, at least twice a month. Egg clusters stuck to the base of the feathers count.
- Lice have six legs and run fast. Mites have eight, and the red mite hides in cracks by day, so you need a flashlight after dark.
- A good dust bath cuts a hen’s lice a lot. The hen that can’t groom or won’t bathe carries the most.
- If you treat, treat every bird the same day with a product labeled for poultry. Then treat again after the eggs hatch, by the label, and follow its egg withdrawal time. We aren’t vets.
Lice Ride In on a Bird or Its Crate
Lice don’t move house much. UC’s guide says a poultry louse usually goes from egg to adult on a single bird, and it “will die within a few days to a week if separated from a host.” Kentucky says about the same thing: “they can survive off of the host for about a week so they can be carried in transport cages or left in shelters.” Merck rounds it to about a week, too.
So where do they come from? Merck’s answer is short: “Lice are usually introduced to a farm through infested equipment (eg, crates or egg flats) or by galliform birds.” Galliform birds are the chicken’s wild cousins, like turkeys and quail. That part isn’t just theory, either. A 2006 study caught 113 wild turkeys in three state parks in Sonoma County, California. One in eight of the lice collected off them was the chicken body louse. Merck calls that one the most common and costly louse on chickens.
Plenty of backyard flocks have lice right now. UC Riverside researchers checked five birds on each of 20 backyard properties across southern California, in summer. “Only four premises (20%) were entirely free of ectoparasites.” That count takes in mites and fleas along with lice. The chicken body louse turned up on half of the properties, and some birds carried dozens to hundreds of them.
Here’s the part I’d hang on to. A louse can’t live long off a bird, so a dirty coop doesn’t breed lice. A bird brought them, or something a bird rode in. That’s my read of these sources, and it changes where you put your effort.
It also means you won’t take them home on your sleeve. Merck says “Humans and other mammals can temporarily harbor avian lice.” Colorado State puts it plainly: “If a poultry louse climbs on you, it won’t stay long.” UC says “Poultry lice cannot survive on humans” or on pets that aren’t birds. So the dog and the cat are safe.
What You’re Looking For, and Where
A chicken louse is small, but you can see it. Arizona’s extension guide puts lice at 2 to 3 mm long, “the size of a sesame seed”. They’re yellowish and they move fast. UC calls them straw-colored and wingless, with a flat body. They have six legs. The chicken body louse, the common one, is 3 to 3.5 mm long as an adult, according to both Merck and UC.
Where you look matters more than what you look for. Merck says the body louse lives mainly on the skin around the vent, plus the breast and thighs. Its advice for checking is “Examination of birds, particularly around the vent and under the wings, reveals eggs or moving lice on the skin or feathers.” So pick the hen up, turn her over, and part the feathers right down to the skin. A glance at the outside of the feathers won’t show you much.
The eggs are often easier to spot than the lice. UC says the body louse glues its eggs in clusters to the base of the feathers, mostly around the vent. “Each egg is less than 1 mm long.” Georgia’s extension tip sheet says “Eggs may appear as dirty gray areas at the base of the feathers, particularly around the vent.” So a grubby clump right where the feather leaves the skin is worth a closer look.
How often should you check? UC says “Birds should be checked for lice at least twice a month.” It also tells you when it’s time to act: “The presence of some lice on most birds or of egg clusters on one or more birds is enough to indicate the need for treatment.” Fall and winter deserve your closest look. UC says louse numbers “tend to be greatest during the autumn and winter.”
As for food, UC says poultry lice chew. They eat dry skin flakes and bits of feather, and they take blood when the skin or a feather quill is broken. Merck says body lice “feed on blood by chewing on pin feathers.” Kentucky’s fact sheet says the opposite, that “they are not blood feeders.” So the sources don’t fully agree on blood. They all agree lice chew, though. None of them says lice pierce the skin and suck, the way the old page did.
The sources don’t agree on timing either. UC says louse eggs hatch in 4 to 7 days, and the young take 10 to 15 more days to grow up. “An adult louse can lay from 50 to 300 eggs in its 3-week lifespan.” Kentucky says the whole life cycle takes 1 to 2 weeks. Texas A&M puts egg to adult at about 30 days. What matters for you is the hatch. Eggs that live through a treatment hatch within a week or so, and that’s why UC warns a single treatment may not be enough.
A heavy load of lice does real harm, too. Merck says it cuts egg production in hens and weight gain in young birds. The itchy skin can pick up bacterial infections. Our page on Rhode Island Red egg production has the University of Florida’s numbers on how much laying lice can cost a flock.
Lice or Mites? Take a Flashlight Out After Dark
People mix up mites and lice all the time, and the fix isn’t the same. So it’s worth a minute to tell them apart. UC says mites are arachnids, not insects, “so an adult mite has eight legs while an adult louse (an insect) has only six.” Arizona’s guide makes it easy to remember. A mite is about the “size of a ground pepper” and moves slowly. A louse is about the size of a sesame seed and moves fast.
The chicken mite is the sneaky one. Folks also call it the red mite or the roost mite. It feeds on the birds at night. By day it hides off the bird, “especially in cracks and crevices of surrounding woodwork,” UC says, or in the nests. That’s why you can check a hen at noon and find nothing. UC’s advice is simple: “Usually you have to inspect your birds at night to find them on the skin.” So go out with a flashlight after dark, and check the cracks in the roost bars while you’re there.
The northern fowl mite is a different animal. UC says it “can be found on poultry both day and night”. It’s worst around the vent, where it can turn the feathers black with dried blood and mite droppings. A bright flashlight helps with this one as well. UC says the light makes mites move around, and that makes them easier to see.
Here’s why the difference matters. Red mites live in your coop, not on your hens. UC says adult chicken mites “can survive up to 34 weeks of starvation,” so an empty coop can stay infested for months. For them, the treatment has to reach the bedding and the woodwork, not just the birds.
Lice are the other way around. Kentucky says it in one line: “Control of NFM and lice is focused on the birds.” A louse that drops into the bedding is dead within a week or so. So scrubbing out the coop every few weeks, like the old page told you to, isn’t the lice cure. Fresh bedding is still a good habit (I’d never argue against that). It just won’t fix lice on its own.
Our page on chicken roost ideas shows how to set a roost bar in brackets so you can pull it out and check it for mites.
Why One Hen Gets the Worst of It
You might find one hen crawling with lice while her flockmates only have a few. That’s normal, and the sources explain why. A chicken grooms her own lice off. UC says “Effective self-grooming of poultry is an important means of reducing lice.” It also says “Louse populations are generally higher on birds with injured beaks or on those that have had their beaks trimmed.”
A UC Riverside study put numbers on that. The researchers put lice on caged White Leghorn hens and counted them for 9 to 16 weeks. Lice were “at least 10 times lower on beak-intact hens” than on hens with trimmed beaks. Crowding mattered too. Hens kept two to a 25 by 31 cm cage grew “higher numbers of lice (2 to 3 times)” than hens kept alone. The authors tied the beak result to grooming, since a hen with a trimmed beak can’t preen as well.
Broody hens are the other ones to watch. Arizona’s guide says “Pay special attention to brooding hens, which tend to dust-bathe less frequently than usual, making them prone to parasites.” A hen sitting tight on a clutch isn’t out rolling in the dirt. So she isn’t working lice out of her feathers, either.
Sometimes the lice are a sign of something else. UC says “The presence of lice frequently accompanies poor poultry health that is attributable to other causes”. So if one hen is covered and the rest aren’t, I’d ask why she isn’t keeping up. That’s a good question for a vet who sees poultry.
On the bright side, molting helps. UC says “Molting greatly reduces louse populations”. My guess at why is that the eggs are glued to the feathers, and those feathers drop. If you want to know how long a molt runs and when the eggs come back, our Chicken Molting Planner works it out.
The Dust Bath Is Her Own Louse Treatment
A dust bath looks like a mess, but it’s how a hen fights her own bugs. UC Riverside tested that in 2012. Cage-free hens got a dust box of sand mixed with diatomaceous earth (DE for short). Other hens got kaolin clay in the sand instead, or sulfur. “73% of hens used the dustbox at least once.” The results for those hens were big. “All materials reduced ectoparasites on user hens by 80-100% after 1 week of dustbox use.” Ectoparasites just means the lice and mites that live on the outside of the bird.
The catch is in the same study. “Diatomaceous earth and kaolin failed to reduce ectoparasites on non-user hens”. And once the box was taken away, the bugs came back on the hens that had used it. For lice, only the sulfur box helped the hens that skipped it, and only when more of the flock used it. The authors’ take was that dust bathing “is probably adaptive”. In plain words, hens roll in the dust partly to keep their bugs down.
Merck backs this up. It says hens given a dust box of washed play sand with food-grade DE mixed in cut their lice a lot by bathing in it. Texas A&M says “Food-grade diatomaceous earth (DE) in dust baths may also be used as a control method.” If you add DE, follow Merck’s warning: “Diatomaceous earth should be applied in well-ventilated areas only, and the applicator should wear a dust mask.” It’s a fine powder, so wear the mask.
My call from all this is to give your flock a dry spot to dust-bathe all year. A hen with a good bath does a lot of the work herself. A hen who won’t use it, like a broody one, gets nothing from it. She’s the one to check by hand.
Our page on chicken pen ideas covers where a dry dusting corner fits in the run. And our chicken coop ideas page explains how a raised coop leaves a dry, shady spot underneath for dust baths.
Treating Lice: Every Bird, Twice, by the Label
First, the honest part. We aren’t vets, and I can’t tell you what to put on your hens. A vet who sees poultry can, and so can your county extension office. What I can tell you is what Merck and the extension guides say about how to treat, so you know what to ask.
Treat every bird, not just the one you caught with lice. UC says “the entire flock or house should be treated at the same time to prevent the possibility of rapid re-infestation of treated birds.” Kentucky says “Treat all birds at the same time and apply the insecticide so that it reaches the skin.” UC adds that you should part the feathers so the dust or spray gets down to the skin. A dusting on top of the feathers misses the lice.
Then plan on a second round. UC says “Louse eggs are resistant to insecticides,” so they hatch after the first treatment wears off. Merck says “Eggs are not killed, so insecticidal treatment should be repeated after 10 days.” Kentucky says “Check for live mites or lice in 7 to 10 days and make follow-up applications as needed.” The label has the final say on timing. Kentucky’s list for new birds says “Check label for age restrictions of birds and re-treatment interval.”
Which product? Kentucky’s 2012 fact sheet names a few as examples. It lists permethrin, sold as GardStar or Prozap Garden & Poultry Dust. It lists carbaryl 5% dust. It also lists PyGanic, a pyrethrin product. But it warns that its picks are registered for Kentucky only, and some may not be legal where you live. UC’s guide says “pesticide approvals may change” and tells you to check with your county agricultural commissioner. Kentucky adds that poultry products may not be on the shelf at a garden store: “Check with local farm supply stores for appropriate insecticides.” So read the label in your hand at your own feed store.
Make sure the label says it’s for poultry, and do what it says about eggs. Arizona’s guide says “Follow all label instructions, including listed withdrawal times for egg consumption or harvesting birds for meat.” It adds “Withdrawal times begin after the last treatment has been given.” I won’t give you a number for that, because only the label has it. If a label says nothing about eggs from treated hens, I’d ask a vet before eating them.
One more thing from the research. UC Riverside tested permethrin strips sold for backyard and commercial flocks against northern fowl mites. “Permethrin strips had no effect on mite populations.” The authors thought those mites might have been resistant. That was mites, not lice, but it’s a good reason to check that a treatment worked instead of assuming it did. UC says switching between types of products slows resistance down.
Keeping the Next Lice Out
Since lice come in on birds, your best guard is at the gate. Kentucky’s advice on new birds is blunt: “Assume all birds that you purchase are infested.” It says to look them over before you buy and to pass on any that are clearly lousy. Then it says to treat them and “Keep newly-purchased birds away from others in the flock until the treatment course is completed.”
Colorado State gives you a time frame: “Quarantine all new birds for 30 days before letting them meet your flock.” It also says to “Inspect new birds for external parasites at least twice during the quarantine period” and to treat them if they need it.
Don’t forget what the birds came in. Kentucky says to clean the crate or box new birds rode in, or throw it out, mainly with mites in mind. Merck names crates and egg flats as the usual way lice reach a farm. If I were you, I’d keep used egg flats from other flocks away from the coop.
Wild birds are the other door. Colorado State says “Discourage wild birds from hanging out with your flock.” Kentucky says to keep them away from your chickens and their feed. UC says that once you’ve treated, you should keep wild birds and other poultry from reaching the flock. Remember those Sonoma County turkeys with chicken lice on them. If wild turkeys wander through your yard, keep them out of the run and away from the feeder.
Then keep up the checks. Twice a month, pick up a few hens and part the feathers around the vent and under the wings. It only takes a few minutes. Kentucky’s fact sheet warns that “often the problem is severe before it is recognized.” A quick look every 2 weeks is how you catch a few lice before there are hundreds.
If a hen looks sick, or the lice keep coming back after you’ve treated by the label, call a vet who sees poultry. We aren’t vets, and nothing here replaces one.
Sources
- Amy C. Murillo, Merck Veterinary Manual: Lice of Poultry (reviewed January 2026).
- McCrea and colleagues, University of California: Common Lice and Mites of Poultry (Publication 8162, 2005).
- Lee Townsend, University of Kentucky: External Mite and Insect Parasites of Backyard Chickens (ENTFACT-516, 2012).
- Shujuan Li and Jennifer Weber, University of Arizona: Protecting Your Flocks from External Parasites (AZ1858, 2020).
- Colorado State University Extension in Boulder County: Poultry External Parasites.
- Gregory S. Archer, Texas A&M: Common External Parasites in Backyard Poultry (2017).
- University of Georgia: Controlling Poultry Lice and Mites (May 2010).
- Murillo and Mullens, Journal of Medical Entomology (2016): ectoparasites on backyard flocks in California.
- Murillo and Mullens, Journal of Economic Entomology (2016): sulfur dust bags.
- Martin and Mullens, Medical and Veterinary Entomology (2012): housing and dust bathing.
- Mullens and colleagues, Poultry Science (2010): beak condition and cage density.
- Lane and colleagues, Journal of Wildlife Diseases (2006): wild turkeys in California state parks.
Sources checked October 30, 2026. The read on where lice come from is mine, from these sources. So is the call on which hen to check first. We aren’t vets. If a hen looks sick, or the lice keep coming back after you’ve treated by the label, call a vet who sees poultry.
Related read: How to Raise Chickens for Eggs — Instant PDF download. Secure checkout by Stripe
