By Kimberli Allen
The mere thought of lice on chickens strikes fear in the heart of every chicken owner and gives rise to so many questions.
So how do we identify, prevent, manage, or treat our chickens against this most common culprit – chicken lice? We asked Dr. Amy Murillo of the University of California at Riverside (UCR) to help us answer these questions.
Types of lice on chickens
The “External Parasites of Poultry” publication by PE Kaufman of the IFAS Extension at the University of Florida lists several species of chicken lice, including:
- Chewing or Biting Louse (commonly referred to as Chicken Body Louse or CBL)
- Shaft, Fluff and Wing Lice
- Chicken Head Louse
These lice are from the suborder of avian lice called Mallophaga. They typically have a short life cycle of 2 – 3 weeks but can live on the host for several months surviving on feathers and bits of dead skin. Off host, these ectoparasites usually only survive for about a week.
Figure A. Chicken body louse – Menacanthus stramineus
Figure B. Female fluff louse – Goniocodes gallinae
Figure C. Chicken shaft louse – Menopon gallinae
Figure D. Chicken wing louse – Liperus caponis
Figure E. Chicken head louse – Cuclotogaster heterographus
According to Dr. Murillo, the most common types of lice seen on backyard chickens are the chicken body louse (Menacanthus stramineus; fig. A), fluff lice (Goniocodes gallinae; fig. B), the shaft louse (Menopon gallinae; fig. C), the chicken wing louse (Liperus caponis; fig. D), and chicken head lice (Cuclotogaster heterographus; fig. E).
In a survey of backyard flocks done in Southern California, the most common louse infesting chickens was identified as the chicken body louse, or CBL. This species is quite cosmopolitan and is seen globally. However, the other species, although rare in commercial flocks, were seen in backyard chickens, as well.
Chicken body lice visually appear flat and tend to be yellow or brown in color. They are relatively small with an adult louse measuring 3 to 3.5 mm in length. However, they can be seen with the naked eye, especially at the base of feather shaft near the skin and especially around the vent. Also, unlike mites, lice are not obligate blood-feeding ectoparasites. CBL feed on the fluff, shaft, and cuticle of feathers, however body and shaft lice can also feed on skin and other dead tissue, as well as blood, by chewing on the skin or pinfeathers. An infestation will cause irritation, including loss of feathers and fluff insulation, possibly causing a reduction in egg production as well as reduced reproductive potential in roosters. A very large population of lice on a chicken can also cause irritation to the point where secondary infections can become a problem. When checking your chickens for lice, you need to look at the base of the feathers and in the fluff of the head, abdomen, under the wings and vent area. Lice will be clustered but moving.
Chicken lice tend to be species-specific. However, according to Dr. Murillo, “we do see some crossover from, like turkeys – other galliforms.” Interestingly also for backyard flocks in particular, “we don’t know how lice are getting there.”
Unlike chicken mites which have a broad avian host range, as we don’t think they could be on the same variety of birds. Like, we don’t see chicken lice on passerine birds [perching birds].” However, lice, though not able to live on humans for any real length of time, can “hitchhike” on humans and equipment, and survive for short periods to later be introduced to your flock in that way.
How do you prevent chicken lice?
So, let’s talk about prevention. Prevention is the key ingredient to anything health-related, be it humans or your chickens. If you can prevent your flock from over-parasitization, you will have much healthier birds. How can we accomplish this?
Well, first up is practicing at least a moderate level of biosecurity. Ensure that your birds’ environments are clean and managed regularly. Ensure that you are checking your flock regularly for signs of parasites (internal and external) and illness.
Secure your birds to prevent predation by other pests and animals. Make sure that you are rotating your flock onto clean pasture. Remove manure from your coop and chicken yard on a regular schedule. And air out your coop regularly.
Also, if you will be introducing new birds to your flock, Dr. Murillo suggests, “quarantining new birds until you know that they’re not infested and bringing new parasites to your flock.” Also, “You don’t want to go from your flock to your friend’s flock in the same day without precautions like changing clothes [or] cleaning yourself between flocks,” says Dr. Murillo. This prevents cross-contamination from one group to another.
Management as a part of prevention is important, as well. In fact, according to Dr. Murillo, chicken lice are much more easily managed than chicken mites. Lice populations tend to develop slowly over 6 to 8 weeks. Whereas with chicken mites you can see an explosion in numbers in a matter of a few weeks. You can drastically reduce the number of lice on your chickens by catching an infestation early through regular health and housing checks.
How do you treat lice in chickens?
In addition to good animal husbandry and biosecurity practices, there are some treatments shown to be incredibly effective in preventing, or at least reducing, lice on your chickens. In 2012, B. Mullens and C. Martin published an article in the journal, Medical and Veterinary Entomology, looking at the effects of dustbathing in caged and free-range flocks of chickens. They compared louse and mite loads in chickens with no access to dust boxes in both groups to chickens with free access to dust boxes each with either added dry sulfur, diatomaceous earth (DE), or kaolin clay.
All three components are naturally occurring materials that when introduced to flock dust boxes were observed to reduce CBL by an average of 88% amongst the three dustbathing groups. Sulfur showed the added benefit of being dispersed by dustbathing chickens to other chickens and their living environment. However, DE and kaolin showed similarly robust reductions in lice loads.
It is important to keep in mind that although these three dry ingredients are all naturally occurring, they can cause respiratory issues. If you use these products, use them as prescribed and wear the appropriate protective equipment such as a dust/mist mask and protective eyewear at a minimum.
There are other over-the-counter treatments approved for use on chickens including those containing the active ingredients permethrin, spinosad, or spinosyn. Dr. Murillo does emphasize, “The important thing is that the label says you can use it on chickens.”
Also important is that these treatments need to be applied multiple times to catch both the nymph and adult cycles as they do not have any effect on the egg stage of chicken lice. It should also be noted that chicken lice products seem to work well if used as directed, whereas treatment failure and resistance continue to be issues with the treatment of chicken mites.
Another important point to make is regarding withdrawal periods post lice treatment for chicken eggs or meat. According to Dr. Murillo, each product should list any egg or meat withdrawal times if it is an approved insecticide for use on chickens, and that typically those treatments that are used externally do not have withdrawal times, but ingested or injectable treatments do have significant periods of egg/meat withdrawal. The treatment methods listed above are all approved, have been shown effective in marked reductions of infestations, and have no egg or meat withdrawal considerations.
Although lice may not seem to be as much a nuisance to your flock as say, chicken mites, they can still cause preventable symptoms in your flock such as a reduction in egg numbers, feather loss, and possible secondary infections.
We thank Dr. Murillo for her time and expertise in helping us demystify chicken lice and how to successfully identify, manage and treat your chickens against this common ectoparasite.
Amy describes herself as “one of those rare people that when I was a kid, I was like, bugs are fascinating, and I want to study them. And I never deviated from that.” She holds three degrees in Entomology. She obtained her first degree in Entomology from Purdue University and then went onto graduate school at NC State studying turf grass entomology. She liked the research and problem-solving aspects of pest management but was not so interested in keeping golf greens and peoples’ lawns in tip top shape. So, she left North Carolina for California to work with Dr. Brad Mullens, a veterinary entomologist at UCR where she began working on a project studying mites on chickens. Her PhD studies focused on chicken parasites like lice. And, now as a faculty member at UCR she continues her work on animal parasites and their impact on health, and importantly as disease vectors.
When California began to experience outbreaks of Newcastle disease, the state made a push for greater education for backyard chicken owners and Dr. Murillo became very interested in understanding backyard flocks as they are so different from commercial poultry. Unlike commercial birds, backyard chickens are usually allowed free range and can encounter wild animals and pasture allowing for exposure to a greater diversity of ectoparasites such as mites, ticks, fleas, and lice.
Did you know that the top five causes of mortality in chickens can be mostly prevented by management? Check out Preventing the Top 5 Causes of Chicken Death
1Murillo, Amy. Interview. Conducted by Kimberli Allen. Interviewed on 22 March 2023.
2Kendra N Chambless, Kevin A Cornell, Rocio Crespo, William E Snyder, Jeb P Owen, Diversity and Prevalence of Ectoparasites on Poultry from Open Environment Farms in the Western-United States of Washington, Idaho, Oregon, and California, Journal of Medical Entomology, Volume 59, Issue 5, September 2022, Pages 1837–1841, https://doi.org/10.1093/jme/tjac093
3MARTIN, C.D. and MULLENS, B.A. (2012), Housing and dustbathing effects on northern fowl mites (Ornithonyssus sylviarum) and chicken body lice (Menacanthus stramineus) on hens. Medical and Veterinary Entomology, 26: 323-333. https://doi.org/10.1111/j.1365-2915.2011.00997.x
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