This article on common poultry mites is an excerpt from the Small Flock Poultry Health Manual published by the Province of B.C. Ministry of Agriculture. The full manual can be accessed by clicking here.
Mites are very small (just visible without magnification) and may appear like moving dark specks. While common poultry mites are wingless like lice, their body shape differs greatly from lice. In addition to their much smaller size, mites have a generally rounded body shape and lack an obvious body segmentation. Also, adult mites have eight legs while adult lice have only six. Mites are not as host specific as lice and may parasitize many animal species. Some mite species spend their entire life on a single bird, while others are found on the bird only during active feeding periods, retreating to nearby protected locations after feeding. Like lice, mite numbers generally increase during the winter months and decrease in the summer months.
Chicken mite or red poultry mite (Dermanyssus gallinae) is one of the common poultry mites, and is a blood sucking mite that generally feeds on poultry during the night. During the day they may be found hiding throughout the poultry house, especially in cracks and crevices of surrounding woodwork, under dirt or manure, or in nests. This habit of leaving the host after nighttime feeding is diagnostic for this species of mite. Chicken mites appear red (following a blood meal) to black in color, and can often be found clustered together in the environment surrounding the birds. Usually you must inspect your birds at night to find them on the skin. Due to their need to find daytime hiding places, chicken mites are generally not a pest in cage layer operations, but can be quite problematic in breeder operations or other operations where fowl are maintained on litter or have nest boxes. Chicken mites have a broad host range and are often associated with a number of wild birds in addition to poultry.
This mite can complete its life cycle in as little as 7 days. Adult females lay eggs in small groups in the environment surrounding their avian host. Eggs hatch in approximately 2 days, and the larvae molt in 1 to 2 days without feeding. All other life stages of this mite feed on blood. Adult chicken mites can survive starvation up to 34 weeks allowing them to survive periods where nests or poultry houses are unoccupied. This makes treatment of the entire poultry facility imperative to controlling this pest. Because chicken mites feed at night, poultry workers are rarely bitten during the workday. However, workers entering into infested poultry houses at night will be readily bitten. These bites may be painful, cause irritation and itchiness, and may result in small red skin lesions.
Northern fowl mite (Ornithonyssus sylviarum) is a blood sucking mite that can be found on poultry both day and night. This mite is commonly found infesting birds in commercial egg-laying facilities throughout California and is arguably the most important external parasite of caged poultry in the State.
Heavy infestations of northern fowl mite are especially costly when birds are beginning to lay eggs. Northern fowl mites appear red to black in color, like chicken mites, but can be distinguished by their daytime presence on poultry, poultry eggs and cage structures. Heavy infestations of northern fowl mite on poultry can result in blackened feathers due to the accumulation of dried blood and excretions, often near the vent, with scabbed and cracked skin around the vent. Eggs and mites are commonly found under the wings, next to the soft feathers of the body, in the feathers above and below the vent, in the beard and crest (on breeds that have them), and on feathers that are high on the legs. Use of a bright flashlight when examining birds for mites will stimulate the mites to move around and make them easier to see. Younger birds generally have greater numbers of mites than older birds. Northern fowl mites have a broad host range and are often associated with a number of wild birds in addition to domestic fowl.
This mite can complete its life cycle in less than 7 days and includes only one blood feeding stage other than the adult mite. Adult mites lay white or off-white eggs in bundles on the fluff surrounding the feather shaft. If this pest is present, all birds in the flock should be treated twice on a 5-7 day interval. Adult northern fowl mite can only survive starvation for up to 2-3 weeks, thus removal of poultry from an infested facility for over 3 weeks will result in control.
Because northern fowl mite is active during the day, poultry workers will often complain of picking up mites while handling eggs or birds during the day. These mites will only occasionally bite humans causing small red skin lesions and intense itching. More importantly, northern fowl mites cause annoyance and concern to poultry workers and their presence may result in the reluctance of poultry workers to continue working. Many poultry workers wrap their forearms with double sided tape or spread a Vaseline-like gel on their forearms to capture mites traveling up their arms when handling mite infested birds, eggs, or cage structures.
Scaly leg mite (Knemidocoptes mutans) is a very small mite with an oval shaped body and extremely short legs. The mite’s entire life cycle is spent burrowing in the unfeathered, scaled skin of the feet and shanks or occasionally the cere and beak. Individual birds contract the mites through prolonged direct contact with other birds and infested surroundings. Older birds are most commonly affected. It is uncommon to find these mites on birds in commercial operations because commercial poultry are generally young and because they rarely have direct contact with older birds infested with this mite. These mites are too small to see without a microscope and often the first indication of parasitism is a brittle, flaky, or powdery appearance to the bird’s legs. This appearance may progress to the formation of lesions or scabs, to lumpy, crusty, proliferative masses, and finally to deformation of the shank and crippling. Suspect lesions on the feet and shank of the bird can be scraped from the leg, placed into a small vial and shipped to a veterinary facility for microscopic examination to determine if these mites are present.
In addition to the treatments listed below for common poultry mites, affected birds should be isolated or culled. For small numbers of birds, scaly leg mites can be treated by direct application of an oil based product such as petroleum jelly, a 50:50 kerosene and cooking oil mix or Blue Ribbon (a mixture of plant oils and camphor in a canola oil extract). While wearing gloves, apply the treatment to the entire affected area daily for at least 2 weeks. After letting the treatment soften the dead scales, gentle scraping or rubbing will help remove the dead scales and mites. Removal of dead scales by soaking the legs in warm soapy water before treatment has been reported to improve treatment results.
Brigid McCrea, Graduate Research Assistant, Poultry Science Department, Auburn University
Joan S. Jeffrey, former Extension Poultry Veterinarian, University of California at Davis
Ralph A. Ernst, Extension Poultry Specialist, University of California at Davis
Alec C. Gerry, Assistant Veterinary Entomologist and Extension Specialist, University of California at Riverside