Mites
Ornithonyssus spp remain on chickens permanently. Dermanyssus mites parasitize chickens nocturnally. Heavy mite infestation is characterized by anemia and the appearance of black mite exoskeleton casts and excreta in the vicinity of the vent.
Argasid Ticks
Soft-shelled ticks (Argas spp.) occur in tropical areas and may affect cage-housed laying flocks or birds maintained on litter. Argasid ticks are nocturnal feeders and favor the soft unfeathered skin beneath the wings. Parasitized birds show multiple hematomas associated with feeding sites. Ticks transmit spirochetosis.
Treatment
Ectoparasites may be treated with a carbamate insecticide such as Sevin®, applied as a 5% powder to birds at two week intervals. Cages and housing can be treated with 2 - 7% carbamate suspension administered by spray.
Only approved insecticides should be applied to poultry or used in the vicinity of housing to avoid contamination of the food chain. Insecticides should be used in accordance with manufacturers' label instructions.