BITING LICE

Mallophaga - biting lice - are probably better thought of as chewing lice as they are not blood feeders. They feed on dead skin and fragments of hair or feathers. They are found on mammals and birds although the majority are found on birds. Eyes in Mallophaga are either absent or very reduced and the mandibles are developed for chewing. The order is divided into the suborders Amblycera and Ischnocera. The Amblycera are generally considered to be more primitive with hosts including birds, marsupials and mammals. Bird lice are characterized by having two tarsal claws on each leg whilst only one tarsal claw is present on lice of mammals. Amblycera feed on skin debris primarily although blood feeding may occur due to the rasping action of the mandibles.

Ischnocera are usually referred to as feather or hair lice as they are adapted to cling onto these structures rather than the skin. Their diet consists of mostly keratin and in order for digestion to occur gut symbionts or specific enzymes are present. Eggs of both suborders are laid singularly and glued to the hosts hair or feathers. They are laid close to the skin as a higher temperature is maintained here. Eggs usually develop in approximately one to two weeks. Total development time from egg to adult therefore takes from three to five weeks. Adult lifespan has been reported to vary from one month to several months.

Heavy lice infections occur predominantly on young or old animals. Those in poor health due to either disease or bad maintenance are also prone to heavy infestations. At present there is no literature which gives conclusive evidence that lice infestations effect production of milk, eggs or beef, although discomfort in heavy infestations will cause a animal to become detracted from normal grazing due to irritation.