Backyard Chickens: A Definitive Guide to Worms and Worming

Updated: 22 March 2021


This article may make you squirm. But we need to talk about worms in backyard chickens. 

In a typical backyard setting, four types of worms can affect your chickens. And not all wormers treat all worms! The treatment you use depends on the type of worm your chickens have.


Before you freak out thinking internal parasites have riddled your flock, they may be completely worm free. It's also possible that they have a few worms or species that won’t cause harm or require treatment. 

In this guide we’ll discuss:

How Do Chickens Get Worms?

How do you know if your chickens have worms?

Types of Worms

3 Steps to Staying on Top of Worms


Our comprehensive guide will dish the dirt on all things worm, so that you and your lovely ladies can relax in complete comfort.


How Do Chickens Get Worms?

  1. Excreted worm eggs from your chickens' faeces can transmit worms. Other flock members can ingest the worm eggs as they scratch and peck at the surrounding litter and soil.
  2. Other worms are ingested via a 'host' such as infected earthworms, ants, beetles, flies, slugs and snails.
  3. Worms thrive in wet conditions. Even if your property is spotless, heavy rains can create the perfect conditions for worm infestations.


A note for breeders: Worms can impact growers’ growth and vitality, particularly between 3 and 9 months. While worms are unlikely to cause death directly, they steal nutrients from your chickens which can decrease immunity and open them up to secondary infections.

If you have slow growers or birds that don't look 100%, worms could be a factor. 


How Do You Know if Your Chickens Have Worms?


Signs your backyard chickens may have worms include:

  • Lethargy 
  • Slow growth
  • Diarrhoea
  • Dirty vents
  • Weight loss
  • Depression

You may see worms in their faeces, but not all worms are visible.


Types of Worms

We’ll list the four most common types of backyard chicken worm in Australia, and some lesser-known culprits. I’ll also suggest the treatment, so you know what to buy for backyard chickens who have worms.

Large Intestinal Roundworm (Ascaridia galli)

These are the most common backyard chicken worm in Australia. They have a direct lifecycle and don't need inserts as a host. 

Symptoms: Often symptom-free, but some hens will look malnourished as worms steal nutrients from the bowel. You may see worms in their faeces. 

Treatment: Kilverm Poultry Wormer


Caecal Worm (Heterakis gallinarum)

These worms live in the caecum of the gut. They have a direct lifecycle and don't need inserts as a host. They are small white-ish worms with a pointed tail, around 7-1.5 cm long.

Symptoms: Diarrhoea, poor growth, depression. Caecal worms cause inflammation in the lower gut. You may see them in their faeces. 

Treatment: Kilverm Poultry Wormer


Threadworms (Capillaria worms aka Hairworms or Capillary worms) 

There are two types of threadworms. Intestinal threadworms have a direct lifecycle, and crop threadworms have an indirect lifecycle through an intermediate host, e.g. earthworms.

Symptoms: Diarrhoea, anorexia (no breast fat), poor growth, look sickly and depressed. Caecal worms cause inflammation in the lower gut. You may see them in their faeces. 

Treatment: Kilverm Poultry Wormer



Can chickens get Tapeworms? Absolutely.

Tapeworms are a problem in Australian backyards, in particular, the tropical parts of Australia. Some types of tapeworm are microscopic; others are up to 15 cm long. 

Beetles, earthworms, slugs, snails, ants and flies etc., can transmit Tapeworms. 

What about us? Can humans get worms from chickens? 

No, chickens cannot transfer Tapeworms to humans. 

Symptoms: Depression, lethargy (tapeworms can produce toxins), unexplained diarrhoea. Generally, tapeworms only affect growth and health when in large numbers.

Treatment: Avitrol Plus Tablets*


Gape Worm

If only I had a dollar for every time people suspected Gape worm! Gape worm is exceedingly rare in Australia. I've never seen a case of it personally, nor has my avian vet. It's more often a case of Aspergillosis in young chickens or older birds. It could be attributed to many respiratory diseases (bacterial or viral) or issues with dust or ammonia. 

Treatment: Avitrol Plus Tablets*. 


Gizzard Worm

 Very rare in Australia; people shouldn't be too concerned about the possibility of infection.  Birds will look anaemic and sickly. 

Treatment: Avitrol Plus Tablets*. 


Eye Worm

These worms can be present in tropical parts of Australia and are transmitted by cockroaches. Worms travel from the gut to the eye, where it causes irritation, itchiness and eventually blindness (due to the bird scratching and damaging the eye). 

Treatment: Physical removal.


3 Steps to Staying on Top of Worms 


There's no point in worming your flock unless you first address their environment and diet. You'll just have the problem return in a few weeks.  

Worms thrive in a compacted, moist and soiled litter. Maintain a clean chicken coop, a good diet, and your flock is unlikely to need constant worming. 

  1. Prevent 

  • Keep housing and run litter dry and brittle. Dryness and sunlight are essential. Ensure you're using appropriate bedding/litter in the chicken coop and the run. 
  • Make sure your chickens' outdoor area drains well after heavy rain. Spots in the chicken coop or run area that don't drain well and are always wet and smelly will cause health problems. You can look at adding corrugated perspex roofing or horticultural plastic sheeting over these areas and then cover them with shade cloth in the summer months.
  • Sand (the coarser or quartz types that drain well) and or wood shavings are great bedding options.

Diet and Feeding 

Studies found chickens that had worms, were often deficient in vitamin A. 

  • Ensure your flock has a balanced diet of grains/pellets, greens and hard and fine shell grit for chickens. Don’t throw feed onto the ground - use a feeder instead. Need advice on feeders? Check out my blog.
  • Keep feeders and drinkers clean. Ask yourself, would you drink it? Raising the height of drinkers may help if they are always dirty. 
  • Avoid overcrowding. Reducing stress in your flock is the easiest way to reduce parasites and illness in your chickens.

2. Test 

Have a professional test your chickens' faeces for worm eggs to give you a holistic view of what's going on. 

A faecal test can be an excellent investment. Before you commit, ask your vet:

  • The cost of a faecal float test

  • Whether they can tell you the types of worm eggs present

  • Whether you'll also have to pay for a consultation on top of the test 

Expect to pay around $50-$73 at Melbourne Bird Vet (no consult necessary). Para-Site Diagnostic Services are also excellent at diagnosing roundworm, caecal worm and threadworms. They don't specifically look for tapeworm but will let you know if they see any. 

3. Treat

How to worm chickens:

Treat your flock using a COMBINATION of natural and commercial worming products. The three commercial wormers I recommend to people, depending on the situation:

  • Piperazine
  • Vetsense Kilverm. A solid choice for the most common backyard chicken worms)
  • Avitrol Plus*. These tablets are popular with Australian poultry breeders. They are easy to use, and you can be confident each bird has received a sufficient dose. Please test before you dose or consult your vet. 

*Avitrol Plus is effective but "off-label" for egg-producing hens. This means a withholding period is not currently available. Use with caution. 

Best natural wormer for backyard chickens

Worming Syrups

Don’t worm on a hot day, and ensure your flock has no access to alternative water sources - that includes puddles! 

Vetsense recommends you withhold water from birds 2 hours before nightfall. Ensure medicated water is available so that the birds can start drinking it in daylight. Replace with clean water after 8 hours or when they have consumed the medication.

Read the directions carefully to avoid under-dosing. This can lead to surviving worms building up a resistance over time. 

Piperazine and Nilverm are both bitter-tasting - your chickens won't enjoy it! 

Fresh Garlic

I do not promote garlic as a wormer, but I believe fresh (not dried or powdered variety) garlic can help prevent roundworms from my experience. Perhaps it's the sulphur-containing amino acids or copper - whatever it is, it works! 

Simply chop one clove per 4-6 hens into small slices or small chunks. Have two drinkers - one with plain water and add the garlic to the other. This gives them a choice; garlic or no garlic. The garlic will float to the top of the water.

If your birds are craving it, they'll eat it, and if not, they won't! Repeat this process daily until they are no longer interested in it. 

Diatomaceous Earth (DE)

DC is an interesting organic resource I'll be exploring more in the future. DC Bennett from the Avian Research Centre at the University of British Columbia in Canada found that adding 2% DE to chicken feed reduces caecal and threadworms in less hardy chickens.

Only ever use 100% Organic Food-Grade DE. Never use commercial pool filter quality DE. 


There you have it! That’s everything you need to know about worms and worming your backyard chickens.

Want your chickens to be the healthiest and happiest they can be? I offer backyard chicken workshops, online programs, phone coaching and in-person support to families, schools and free-range egg farmers. 

Check here for the latest tips and trends all about chooks. Become an expert in Backyard Chickens 101 in just 30 minutes with our new e-book. Order yours now!

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Elise McNamara, Chicken Consultant & Educator.

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