Avian lice, which belong to the suborder Mallophaga, have a life cycle of ~3 weeks and normally feed on feathers or bits of dead skin. Lice may live for several months on the host but remain alive for only ~1 week off the host. People and other mammals may harbor avian lice but only temporarily.
The most common and economically important louse to both chickens and turkeys is the chicken body louse, Menacanthus stramineus. This louse is found in intensive commercial flocks and in small backyard or hobby flocks alike. Adults are 3–3.5 mm long, and eggs are glued to the base of feathers. This species is found primarily on the host’s skin in the vent, breast, or thigh areas. Chicken body lice feed on feathers and also blood feed by chewing on pin feathers.
Several other species of lice can infest domestic poultry. Comparatively little is known about these species because they are rarely seen infesting commercial flocks, and it is unlikely that they are of major economic importance, with the possible exception of Menoponidae lice (Menacanthus spp, Menopon gallinae) which can blood feed.
Chickens are less commonly infested with the shaft louse Menopon gallinae (on feather shafts), the chicken wing louse Lipeurus caponis (mainly on the primary wing feathers), the chicken head louse Cuclotogaster heterographus (mainly on the head and neck), the fluff louse Goniocotes gallinae (very small, in the fluff of feathers), the large chicken louse Goniodes gigas louse), the brown chicken louse Goniodes dissimilis, Menacanthus cornutus, the small body louse Uchida pallidula, or Oxylipeurus dentatus. Turkeys may also be infested with the large turkey louse Chelopistes meleagridis and the slender turkey louse Oxylipeurus polytrapezius.
Because lice transfer from one bird species to another when the hosts are in close contact, other domestic and caged birds may be infested with species of Mallophaga that are usually host-specific. Lice also sometimes reach new bird hosts by using louse flies (Hippoboscidae) for transportation. Some lice of geese and swans are vectors of filarial nematodes.
Heavy populations of the chicken body louse decrease reproductive potential in males, egg production in females, and weight gain in growing chickens. Areas of skin irritation are also sites for secondary bacterial infections. Other species of lice are not highly pathogenic to mature birds but may be fatal to chicks. Examination of birds, particularly around the vent and under the wings, reveals eggs or moving lice on the skin or feathers.
Lice are usually introduced to a farm through infested equipment (eg, crates or egg flats) or by galliform birds. Lice are best controlled on caged chickens or turkeys by spraying with insecticides. Eggs are not killed, so insecticide treatment should be repeated after 10 days. Birds on the floor are more easily treated by scattering insecticidal dust on the litter or by providing dustboxes containing sand and an insecticidal dust, such as diatomaceous earth or sulfur dust.