External parasites in chickens

Ornthonyssus sylviarum: Northern fowl mite

The northern fowl mite is the most common external parasite found on chickens. They are more plentiful in winter and spring, but severe infestations can be year-round. Northern fowl mites are fast moving and can be found around the vent. One of the tell-tale signs is the abundant amount of feces left behind. Northern fowl mites are obligate blood-sucking parasites which spend their life on the host. There are 4 stages in the mite life cycle: egg, larva, nymph, and adult; each occur at the base of the feathers. Mites are transmitted by bird-to-bird contact or by the mite crawling to a new host. These mites can transmit diseases such as fowl pox, fowl cholera, and Newcastle disease. The northern fowl mite can also bite rodents and people. Bites from a northern fowl mite can cause itching and skin irritation. Carbaryl is no longer approved for use on chickens, and macrocyclic lactones like ivermectin require high, nearly toxic, doses and are not approved for use on chickens. Some permethrin products are not approved for hens laying eggs for human consumption. Diatomaceous earth can be used as a preventative in a dust bath, but it is not effective in large infestations. Since the mite life cycle is 7 days, it is necessary to re-treat birds every 4-7 days.  

Echidnophaga gallinacea: Stick-tight flea

A stick-tight flea can be found embedded in the fleshy parts of the head around the eye. When chickens scratch at the irritation caused by fleas, that opens the skin to infection which can lead to blindness. Young chickens may succumb to anemia. Stick-tight fleas spread by hopping around freely until finding a suitable host for breeding. Flea eggs fall to the ground where the larvae develop in soil around the chicken coop. Adult fleas emerge from the soil after two weeks and seek a host. Chickens can be suspended in cages 3 feet off the ground to minimize chances of stick-tight flea infestation. To kill adult fleas, apply a product that is registered for on-animal use or coat adult birds with petroleum jelly. To eliminate flea larval development, treat the premises with an insecticide registered to treat outdoor areas. Work with your veterinarian to develop a treatment plan.

Knemidocoptes mutans: Scaly leg mite

Scaly leg mite is a common ectoparasite found in adult backyard birds. These mites cannot be seen with the naked eye. The mites spend their entire lives burrowing under scales on lower legs and feet. This burrowing action causes damage to the skin, causing the scales to bulge and toes to become deformed. Scaly leg mite is transmitted bird to bird or from infected soil. To minimize the chances of scaly leg mite infestation, chickens may be housed in cages that are three feet off the ground. Diagnosis can be made by microscopic identification. To kill mites, apply linseed oil or petroleum jelly to the chicken legs and repeat every 7 days for 3 weeks. Work with your veterinarian to develop a treatment plan that is right for your flock.

Menocanthus stramineus: Chicken body louse and Menopan gallinae: Shaft louse

Chicken body louse and shaft louse are two types of chicken lice that are similar in body composition which makes it difficult to distinguish each. They live and complete their life cycle on their host. Lice survive by chewing on feathers and dry skin which leads to feather loss, decrease feather insulation, and reduced egg production. Lice can be found by holding the wings out and up so that the primary feathers are held back. Look for clumps of eggs at the base of feathers in addition to active lice. Some permethrin products are not approved in hens laying eggs for human consumption. Diatomaceous earth can be used as a preventative in a dust bath but is not effective in large infestations. Since the mite life cycle is 7 days, it is necessary to re-treat birds every 4-7 days. Work with your veterinarian on a treatment plan for your flock.

Dermanyssus gallinae: Chicken mite or red mite or roost mite

Red mites infect domestic and wild birds worldwide. They are nocturnal feeders and can be found hiding in the cracks and crevices of chicken houses. The female mite must consume a blood meal before laying eggs in the crevices that will hatch after 2-3 days. Larvae will molt into nymphs in 1-2 days. Nymphs will feed off the host and will emerge as adults in 4-5 days. Red mite adults can live for 8 weeks to 5 months without consuming a blood meal. Diagnosis involves putting double-stick tape on perches or cages to capture mites. Treating the coop with pyrethroid pesticides and sealing the crack and crevices will help control infestation.

Argas persicus: Fowl tick

A fowl tick is a soft tick that is reddish brown to brown with wrinkled skin. Female ticks can lay 30-100 eggs per batch, and they will need a blood meal in between egg batches. The life cycle of the fowl tick from egg to adult is 30 days. A fowl tick can engorge itself on the host in 30 to 45 minutes. Adults can survive up to a year without a blood meal. Fowl tick infestations can lead to anemia, weight loss and reduced egg production. While treating the hen directly won’t resolve the infestation, cleaning the coop with pyrethrin will help kill any ticks.

Bed bugs (Cimex sp.)

Bed bugs are usually found in large numbers and are reddish brown. A female can lay 15-69 eggs at a time in cracks and can lay 150 – 600 eggs during her lifetime. A bed bug can go from an egg to adult in 1-4 months. Bed bugs can withstand 1 to 5 months of starvation. Bed bugs can engorge themselves in 5 to 10 minutes. Bed bugs can be transmitted from chickens to humans. Bed bugs can feed on humans and their bite will cause a reddish rash to form. To kill bed bugs, clean and treat the coop with insecticides. Work with your veterinarian on a treatment plan.