By Diane Schivera, M.A.T.
This summer I got many calls from chicken owners about ectoparasites. These pests are rarely problematic in the summer when birds have access to the outside, with sunshine and many places to dust bathe. However, folks in other New England states had the same comments this year. The cause is a mystery, although the wet weather may be one explanation.
Ectoparasites are critters that live primarily on the outside of the animal. Two major types infest poultry: lice and mites. Both feed on feathers, dead skin, blood or scales and cause, primarily, loss of production of both growth and eggs. Young birds with serious infestations can die.
Lice are found on the skin and feathers and can move from one bird to another when birds are kept in close proximity. These small, wingless creatures, from 1/25- to 1/4- inch-long, spend their entire life on their host. Different species of lice live on particular parts of the chicken’s body. Body lice, Menacanthus stramineus, chew on the chicken’s skin and leave scabs. Head lice, Cuclotogaster heterographus, are serious for young chicks of breeds with lots of head feathers, e.g., Polish. Other lice live on the feather shafts, wings and “fluff.”
Nit clusters (eggs) are attached to the base of feathers and hatch within four to seven days from being laid. Within about three weeks they have gone through their molts and can lay eggs themselves.
Poultry lice survive for only a few days to a week if separated from their host. They have chewing mouthparts to feed on dry skin, scab tissue and feather bits, and can feed on blood if skin or feather quills are punctured. Lice are generally host specific; they can feed on only one or a few closely related species of animal host.
Mites are also very small – 1/25 of an inch – and even microscopic. They have a round body with no obvious segmentation, and piercing and biting mouthparts. They have eight legs while adult lice have six.
Mites are not as host-specific as lice and can parasitize many animal species. Some mite species spend their entire lives on one bird; others are on the bird only during active feeding periods, retreating to nearby protected locations after feeding.
Red poultry mites or chicken mites (Dermanyssus gallinae) are bloodsucking mites that feed on poultry at night. In the daytime these mites hide in cracks and crevices in the poultry house. This feeding habit is diagnostic for this species. They are grey until they turn red from sucking chicken blood. They can survive off the bird for six months, so can infest housing long after birds are gone. Control these mites by cleaning the house thoroughly (using a permitted substance if you are certified) and cleaning again in five to seven days to kill mites that just hatched from eggs that were laid in the house.
Northern fowl mite (Ornithonyssus sylviarum), a bloodsucking mite, can be found on poultry day and night. If the mite is on the bird during daylight, that is diagnostic for northern fowl mite. It lives for only a month off the chicken so is a bit easier to eliminate, but since it is on the bird its whole life, it can be more damaging than the red mite.
Northern fowl mites and eggs are found under the wings, near the soft feathers of the body, in the feathers above and below the vent, and on feathers that are high on the legs. Using a bright flashlight to examine birds will stimulate the mites to move and make them easier to see.
Knemidocoptes mutans, scaly leg mite, is a 1/100-inch grey mite that lives under the leg scales of the chicken’s shanks. The scales on the legs become raised because mite feces accumulates under them. This mite also spends its entire life on the bird. Smothering can kill it: Use a paint brush to put vegetable or linseed oil on the birds’ legs when they are on the roost at night. Mixing the oil with an essential oil, such as tea tree oil with antibacterial properties, will help the healing process. It is important to repeat this process for three or more nights in a row and again in a week to 10 days.
Organic treatment for all mites and lice except the scaly leg mite is a multi-pronged approach.
For prevention, give birds a generously sized, easily available dust bath. Think about the number of birds you have and their size. The dust bath should contain a sand and clay mixture and should be deep enough that the birds can really dust themselves in it. To increase the effectiveness of the dust bath, you can add 1/4 cup each of diatomaceous earth (DE) and wood ash to each gallon of soil, but don’t add more, because these materials irritate the respiratory system. Wear a dust mask when mixing the dust bath.
For treatment, a pyrethrin product is permitted. Follow the label dilution recommendations for a liquid. Using an essential oil, e.g., peppermint oil, in with a gentle soap as a drench could also be effective. You could also dust the birds with DE – but remember, again, to protect yourself and the birds from this respiratory irritant. Repeat any treatment you choose, twice in seven-day intervals, to kill newly hatched pests, because treatments rarely kill eggs.
The Chicken Health Handbook, by Gail Damerow, Storey, 1994
Common Lice and Mites of Poultry: Identification and Treatment, by Brigid McCrea, Joan S. Jeffrey, Ralph A. Ernst and Alec C. Gerry, University of California Publication 8162, posted at http://ucanr.org/freepubs/docs/8162.pdf
Diane Schivera is MOFGA’s organic livestock specialist. You can contact her at 568-4142 or firstname.lastname@example.org.