How to identify chicken lice and mites and prevent infestation on the farm

Known as ectoparasites because they live on the skin and feathers of animals, chicken lice and mites can be found in structures and even on the litter in barns. In general, mild infestations are easily controlled, and the birds can rid themselves of these parasites through dust bathing and self-cleaning.

Mites, for example, can be removed from feathers through dust baths, highlighting the importance of keeping the litter dry and loose. However, control without clinical intervention is possible only if there are no favorable factors for their proliferation and if the animals are healthy.

Unfavorable housing conditions for chicken rearing or those that do not strictly meet biosecurity measures are critical factors that predispose birds to ectoparasite infestations.

Lice and mites are external parasites that feed on the blood, feathers, or skin scales of birds. They can be found infesting laying hens, or depending on the stages of the parasites’ life cycle, they can also be found in the environment.

Mites can survive up to 10 months in an empty barn, and lice larvae can live in the same environment as the birds; the problem arises when they reach adulthood and infest the flock.

When an infestation occurs, chicken mites and lice cause blood-sucking, weakening the birds’ immune systems, leading to increased susceptibility to other diseases. To avoid this problem, maintaining biosecurity for people and facilities is essential.

Types of ectoparasites and infestation impacts

The negative effects of ectoparasites on chicken welfare are numerous, from persistent stress due to bird disturbance, physiological weaknesses, increased susceptibility to other diseases, reduced productivity, and even death. 

The birds may show signs such as anemia, progressive weight loss, and reduced laying rates. The risk of unidentified and untreated infestations is that, in extreme cases, they can collapse the entire flock.

Types of Lice

The common types of lice that affect wild birds and are most common in laying hens include Menopon gallinae, Menacanthus sp., Goniocotes gallinae, Cuclotogaster heterographa, and Columbicola columbae. The latter, known as pigeon lice, can also infest chickens if pigeons or other wild birds enter the facilities or if there is a failure to disinfect footwear when entering chicken housing. Menopon gallinae and Menacanthus sp. have five life stages: egg, nymph 1, nymph 2, nymph 3, and adult male and female, which live attached to the feathers of laying hens. This type of lice does not survive long in the environment.

Lice are chewing parasites rather than blood-sucking; they live on the birds’ skin, around the cloaca, under the wings, thighs, and chest. They do not survive long in the environment without parasitizing birds. They can cause significant skin irritation, stress, agitation, and compromise animal performance and welfare.

Types of Mites

Red Mite or Chicken Mite (Dermanyssus gallinae):
Also known as “chicken mite,” despite its popular name, it is a mite and not a louse.

These mites hide in coops, barns, and aviaries during the day and climb onto birds at night to feed on blood. They are blood-feeding and can severely weaken chickens.

The complete life cycle takes about two weeks but can be shortened to one week under ideal conditions (35°C and relative humidity above 70%).

Feather Mite (Ornithonyssus sp.):
Known as the “feather mite,” it stays on the bird almost all the time.

It continuously infests the birds, making it easy to distinguish its infestation from that caused by Dermanyssus gallinae.

In addition to poultry, this mite is found on urban pigeons, causing infestations in places such as squares and public parks.

Another Feather Mite (Megninia sp.):
This mite is not blood-feeding.

It spends its entire life cycle on laying hens, living in the feathers. It damages the feathers, leaving them dirty, fragile, and brittle. In Brazil, there is little information about this type of mite.

These mites are important to monitor and control to ensure the health of the birds and the quality of egg production.

Signs of chicken lice and mite presence

The first signs of infestation can be subtle, as ectoparasites are tiny. However, the producer will notice an escalation of common symptoms across several birds:

• Visualization of ectoparasites during a physical examination of the birds;
• Fatigue and apathy;
• Itching (pecking behavior among feathers, leg or foot scales);
• Reduced egg production;
• Red spots on the skin;
• Paleness and regression of combs and wattles;
• Feather pecking;
• Scabs or blood on legs and feet;
• Lice eggs on feather shafts;
• Blood on eggshells;
• Problems and reluctance to perch or use nests if these places are infested with parasites.

How to prevent ectoparasite infestations

Preventive biosecurity measures and regular physical examinations of birds are the best practices for monitoring and preventing lice and mite infestations on your farm. Preventing the entry of wild birds through gaps in netting and door closures limits the transmission of these ectoparasites from wild birds to chickens. Installing bird deterrents helps prevent the entry of other host birds, such as pigeons.

Another potential and important risk is negligence or failure in biosecurity measures such as disinfecting or changing footwear and clothing when entering the chicken environment. These and other objects may be contaminated with different parasites and transmit them from the external environment or from one barn to another.

Effective disinfection of structures and bird access points during the sanitation period is essential to prevent transmission of these organisms to future flocks. Elevated nests and frequent replacement of bedding or mat cleaning prevent the accumulation of parasites indoors.

Constant monitoring of the environment and birds is necessary to identify infestations in time to combat them, that is, at the very beginning. Pay special attention to bird behavior, such as excessive self-cleaning and reluctance to enter nests. Access to dry, loose litter that allows dust bathing is also preventive.

Prevention is the most efficient way to combat the presence of ectoparasites in laying hens at any stage of life.

All the points covered in this article are carefully evaluated during audits by the Certified Humane program, according to the laying hen manual, which can be accessed here.

To help you prevent this type of challenge on your farm and promote comfort and welfare for the animals, read our content on what should be checked daily in laying hen rearing.

Published on February 27, 2025