It seems like everything on earth loves to eat chickens. From wolves and coyotes, dogs and cats, even other birds in the form of hawks, owls, and eagles, and every kind of carnivorous animal in between.
Turns out even the tiniest predators want a bite of our backyard birds, including insects, worms, and even nastier critters besides.
Our chickens, sadly, are vulnerable to more than their fair share of parasites, both internal and external varieties.
These creatures live by living off of our poor chickens, taking nutrients, skin, feathers, or even their very blood as their own food. Aside from being disgusting and unsettling, the damage they can do ranges from annoying to outright deadly.
If you want to protect your flock’s mental and physical health from the scourge of parasites, you’ll need to know what you are looking for. This article will tell you about the top 14 chicken parasites you will need to guard against.
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What Kind of Parasites are we Dealing With?
Regrettably, there are all kinds of nasty, parasitic life forms that can affect your chickens. From subtle, internal parasites like cecal worms to the nasty, harrowing infestation of maggots left behind by botflies.
No matter what kind and no matter their lifecycle, all parasites have one thing in common: they live and thrive at the expense of your chickens.
Parasites invariably inflict harm on their hosts, and though they might not cause serious symptoms, at least at first, things usually get worse when their numbers increase or the health of the host starts to decline, either from their own predations or from other factors such as sickness, stress or age.
A bad infestation of parasites combined with nutrient deficiency and sickness can easily kill a chicken, and young birds in particular.
Learning what these parasites are and the symptoms they cause will help alert you when treatment is needed, and also whether or not DIY natural or over-the-counter treatment is likely to be effective.
Not all parasite infestations can be treated successfully with natural means, however, and you should always consult your vet right away if one of your birds is in bad shape.
Here are some of the most common types of parasites that prey on chickens, categorized into internal and external varieties for your convenience.
Internal Parasites
Parasites that hatch and live out their life and shelter or feed within a chicken’s body or organs are internal parasites.
1. Ascarids (Roundworms)
These are the largest and most common types of worms found in chickens. They measure up to 7 inches in length, and their eggs are very hardy, surviving for years in damp conditions.
Chickens typically pick up these eggs from contaminated soil or droppings while they are scratching around.
The larvae hatch in the chicken’s gut and mature into adult worms, where they lay their eggs. The chicken then passes these eggs out in its droppings, contaminating the ground again. Ascarids may migrate to other areas of the chicken’s body, causing all sorts of issues.
Roundworms usually cause diarrhea, poor appetite, dullness, weight loss, and an enlarged abdomen.
2. Cecal Worms (also called Blindworms or Threadworms)
Tiny, thread-like worms that live in the ceca, pouches found at the junction of the small and large intestine in a chicken that helps absorb nutrients and moisture.
Chickens become infected with these worms when they eat contaminated food or drink contaminated water.
The cecal worm’s eggs are passed out in the chicken’s droppings and can survive for long periods in damp conditions, contaminating the ground. These are the most common and successful parasitic worms in chickens.
Signs your chicken may have cecal worms include blood-tinged diarrhea, increased thirst, dullness, and weight loss.
3. Gapeworms
Gapeworms are one of the more serious infestations a chicken can experience. The larvae hatch in the chicken’s gut and migrate to the trachea (windpipe). They then attach themselves to the mucous membranes, feeding on blood as they begin to grow.
Chickens often get gapeworms from eating infected insects or contaminated food. A heavy infestation of gapeworms can cause a blockage in the trachea, making it difficult for the chicken to breathe. Gapeworms might require special medicines for treatment.
Symptoms include respiratory distress, gasping for breath, open-mouth breathing, coughing or hacking, cessation of eating, and weight loss.
4. Tapeworms
Another common and possibly huge parasite, chickens can get tapeworms from eating infected insects, feces or contaminated food. Once in the chicken’s gut, the larvae attach themselves to the intestinal wall and begin to grow.
A heavy infestation of tapeworms can quickly lead to malnutrition and poor growth in chickens as they rob the chicken of essential nutrients.
Symptoms of tapeworm infestation are most obviously presented as short, white, or yellowish body segments in droppings, and also include increased appetite accompanied by profound weight loss, dullness, and weakness.
5. Eyeworms
One of the most grisly and serious infestations, chickens can pick up eyeworms from eating carrier cockroaches, or by contact with an infected chicken.
The larvae travel through the chicken’s body, up through the throat, and through the sinuses until they reach the eye, where they mature and lay their eggs.
A heavy infestation of eyeworms can cause blindness and death, and these worms cannot be treated with our methods below. Call your vet!
Look for thick, cheese-like discharge from the eye, swelling and inflammation of the eyelids and surrounding tissues, and eyes that are stuck shut.
6. Flukes
Flukes are a type of flatworm that infests the intestines and sometimes the skin of chickens. Though more common in waterfowl, chickens can contract these parasites from contaminated food sources, water, or sometimes wet, filthy soil, and particularly soil that has been contaminated by droppings containing fluke eggs.
Eating infected slugs and snails is another common source of infection. A heavy infestation of flukes can cause all sorts of problems, including anemia, malnutrition, a drop in egg production, and even death.
Unfortunately, there are not many products for treating flukes, and what medicines there are will require a prescription from your vet. Diagnosis is typically done by examining droppings of infected birds for eggs.
To spot an infestation, look for weight loss, loss of appetite, unhealthy appearance, thick discharge from the vent, lethargy, reduced egg production, and an increase in soft eggs among those that do get laid.
7. Histomonas Meleagridis
This nasty microscopic protozoan parasite is infamous for causing histomoniasis- better known as the dreaded blackhead disease.
Though chickens are most often asymptomatic carriers, it can devastate turkeys and is almost always fatal.
However, chickens can be seriously affected by the disease and there are no known cures or vaccines.
In chickens, blackhead causes liver damage and usually paves the way for other bacterial infections which can lead to septicemia (blood poisoning) and death. The disease is spread through contaminated soil, water, or equipment, or by contact with other infected birds.
Again, chickens are usually asymptomatic but they can fall prey to blackhead disease. Look for listlessness, drooping wings, watery yellow diarrhea, and decreased egg production.
Affected chickens will usually show poor overall health for some time after even post-treatment. If you have any suspicion that any bird in your flock is affected you must quarantine them immediately, especially if you also have turkeys!
External Parasites
External parasites are those that prey on chickens on or from the surface; skin, feathers, blood so forth. This category also includes parasites that lay eggs directly on chickens from the outside, like various flies.
8. Fleas
Fleas seem to be the scourge of every warm-blooded mammal on Earth, and regrettably, chickens don’t get an exception.
All fleas bite and drink the blood of their host to survive, and there are many kinds of fleas that will attack chickens for that purpose.
Not only are fleas annoying since their remorseless biting causes itching and skin problems, but a heavy infestation can even cause anemia and potentially death.
Some fleas are particularly persistent, like the sticktight flea, named for its habit of holding fast on a bird despite attempts to remove them directly.
To spot an infestation of these ruthless bloodsuckers, look for tiny brown insects moving or jumping about on your chicken’s skin and feathers, particularly around the vent and face area.
You might also see your chickens excessively preening or scratching themselves. Long torment from fleas might cause birds to pluck their own feathers.
9. Ticks
Another disgusting and common parasite, ticks are similar to fleas in that they dine on the blood of their host to survive.
Unlike fleas however, ticks are the kind to hang around as long as possible, drinking and drinking and drinking until they swell up obscenely before finally dropping off if not removed manually.
There are many different kinds of ticks, from deer ticks to brown dog ticks, and in the right circumstances, most will bother your chickens, causing anemia and stressing out affected birds.
In extreme cases, anemia and death are a possibility again. Most worryingly, ticks are known to transmit various devastating diseases to poultry and people alike, among them Lyme disease, Rocky Mountain spotted fever, and tick paralysis.
Perhaps the only saving grace is that ticks are usually large enough that chickens will happily eat them if they notice them on the ground, though they fare worse trying to get them when concealed beneath feathers.
To find out if your chickens are being bothered by these greedy parasites, look for them on the skin and beneath the feathers of your birds, particularly around the head, neck, and under the wings where they like to congregate.
Also, keep an eye on bedding where ticks might be lurking, and don’t be afraid to remove or treat as needed.
10. Lice
Another entirely-too-numerous insect that feeds on blood, birds are common hosts to these critters. Lice live out their entire lives- birth, maturation, reproduction, and death- on the host chicken and die in a day or two if forcibly evicted.
Like fleas, lice will drive chickens crazy from their constant feeding, and like fleas, they also multiply rapidly.
Lice adhere their eggs directly to the feathers of affected birds where they will prove almost impossible to remove without chemical treatment. That means a small infestation will usually go out of control in short order unless you intervene.
Lice infestation might also cause your chickens to stop laying eggs as the stress of being eaten alive takes its toll.
To find out whether your chickens have lice, carefully part the feathers on different areas of the body and look for small, translucent, wingless insects crawling about.
Look closely, as many lice match the feather or skin color of their hosts- the better to hide! Also, check the base of feathers and the vent of chickens for egg deposits and irritation.
Constant preening, scratching, and potentially plucking is another indicator of lice (or some other external parasite).
11. Scaly Leg Mites
Mites are the second category of parasitic arachnids on our list and come in several terrible varieties that specifically target chickens.
Mites are the most versatile of our external parasites since they might feed on blood, skin, or keratin, depending on the species.
This means that they may potentially infest the entire body of our poor, blighted birds! In the case of the scaly leg mite, they target the legs of chickens, specifically the “shin,” feet, and toes, where they tunnel behind the scales to feed.
This causes scales to lift and die, a buildup of waste matter, irritation, and potentially deformity as the mite’s actions stunt proper growth. In severe cases, scaly leg mite infestations might lead to anemia and lameness.
To detect a scaly leg mite infestation, look for scaly, crusty lesions on the legs of your chickens as well as discoloration and thickening of the skin. Also, look for ulcers or a chicken favoring one leg. If a chicken is unable to stand, they might be in real trouble! I also wrote a dedicated article on how to treat mites in chickens.
12. Northern Fowl Mites
Another mite, and one of the most common that keepers have to deal with on a regular basis.
These mites are incredibly small, active, and voracious, meaning they can do a lot of damage in short order.
These mites migrate to feed, meaning they live on the feathers of affected birds but they travel to the surface of their skin to feed.
Northern fowl mites are the bane of many owners since severe infestations can rob a chicken of up to 6% of its total blood supply! That is hideous beyond imagining from such a small creature.
Found all over the continent, and spread by just about every bird in existence, this is one parasite you will never be truly free of.
All you can hope to do is keep your birds treated and conditions around their living spaces inimical to the little monsters.
Northern fowl mites are fairly easy to spot, particularly when the infestation gets going. Check the vent area of your chickens for dense clusters of small, reddish-brown bugs that are about the size of a pinhead, or cracked and potentially bleeding skin.
Also, watch eggs in laying hens: invariably some mites will be found on the surface of the egg, and easy to spot.
13. Blowflies
Flies hang around barnyard animals like flies on… Well, you know the rest. But in seriousness flies aren’t merely pesty insects that live to annoy; in some cases, they can cause grave harm to animals, especially chickens.
In the form of blowflies, which lay their eggs on the skin of chickens, this is known as flystrike.
Blowflies may be attracted to any injuries whatsoever a chicken has, relentlessly pestering them until it has a chance to land and do its grim, disturbing business.
Often occurring around the vent of an infested bird, when the fly larva hatches as a maggot it burrows further into the chicken’s flesh and starts to grow.
But to do that, it will need food. The food, in this case, is the dead flesh of your chicken’s wound. Devoured alive, too literally!
Blowfly infestation is not easy to spot except in theory: they lay their eggs on the surface of the chicken’s skin, usually near a wound or near the vent, but the eggs hatch in about a day.
You will usually notice a blowfly infestation when you see maggots wriggling and pulsing on or beneath the skin of your poor chicken. This is a medical emergency: serious flystrike from a blowfly can kill in a few days.
14. Screwflies
Another hideous parasitic fly, the screwfly, or more properly screw-worm fly, is a species of fly that targets any warm-blooded creature it can sink its teeth into, or rather its ovipositor.
Screwflies seek to lay their eggs on the skin of your birds which, upon hatching, simply burrow down into the flesh to feed.
Unlike blowflies above, screwfly maggots eat live tissue and can cause lethal damage. They get their name from the fact that, if disturbed while in the wound, they simply burrow deeper and deeper into the flesh of the victim.
Once old enough, they drop from their host and finish maturation outside, before finally reaching adulthood as a fly, continuing their hideous cycle.
Eradicated from the U.S. back in the 1980s, outbreaks are still uncomfortably common and the flies remain in the Caribbean.
Spotting evidence of screwfly infestation is easy enough, if harrowing: simply look for what appears to be a small, circular wound on your chicken or around an existing injury.
If you notice a wriggling little monster in there, one that retreats deeper when disturbed, you have a screwfly victim on your hands. Again, assume the worst and contact your vet right away! Any flystrike in chickens is a medical emergency!
Always Consult Your Vet in Case of Serious Parasite Problems
It should be obvious, but it is worth pointing out that if your chickens are seriously ill from any parasites, or if you have a major outbreak, you should consult a licensed veterinarian.
Do not hesitate to do this because it could mean the difference between life and death for your flock, particularly in the case of eyeworms, gapeworms, and flystrike.
Though many owners of livestock, and perhaps yourself, know good and well how to take care of their animals, including how to take care of parasites, you should not let ego get in the way of the health of your flock. If you have any doubts whatsoever, please summon professional help. Your chickens’ lives might depend on it!
Tom has built and remodeled homes, generated his own electricity, grown his own food and more, all in quest of remaining as independent of society as possible. Now he shares his experiences and hard-earned lessons with readers around the country.
Find out more about the team here.