The primary effects of lice on their hosts are the irritations they cause. The birds become restless and do not feed or sleep well. They may injure themselves or damage their feathers by pecking or scratching areas irritated by lice. Body weight and egg production may drop.
All lice infecting poultry and birds are the chewing type. Mites may be confused with lice, but mites suck blood. In general, each species of lice is confined to a particular kind of poultry, although some may pass from one kind to another when birds are closely associated. Chickens usually are infested with one or more of seven different species; turkeys have three common species.
All species of poultry lice have certain common habits. All live continuously on feathered hosts and soon die if removed. The eggs are attached to the feathers. Young lice resemble adults except in color and size. Lice differ in preferred locations on the host, and these preferences have given rise to the common names applied to various species.
In general, the incubation period of lice eggs is four to seven days, and development of the lice between hatching and the adult stage requires about twenty-one days. Mating takes place on the fowl, and egg laying begins two to three days after lice mature. The number of eggs probably ranges from fifty to three-hundred per female louse.
As the name suggests, the Head Louse (Cuclotogaster heterographa) is found mainly on the head, although it occurs occasionally on the neck and elsewhere. It usually is located near the skin in the down or at the base of the feathers on the top and back of the head and beneath the beak. In fact, the head of the louse often is found so close to the skin that poultrymen may think it is attached to the skin or is sucking blood. Although it does not suck blood, the head louse is very irritating and ranks first among lice as a pest of young chickens and turkeys. Heavily infested chicks soon become droopy and weak and may die before they are a month old. When the chickens become fairly well feathered, head lice decrease but may increase again when the fowls reach maturity.
This louse is oblong, grayish and about 1/10-inch long. The pearly-white eggs are attached singly to the down or at the base of the small feathers on the head. They hatch within five days into minute, pale, translucent lice resembling adults in shape.
The Body Louse (Menacanthus stramineus) of chickens prefers to stay on the skin rather than on the feathers. It chooses parts of the body that are not densely feathered, such as the area below the vent. In heavy infestations, it may be found on the breast, under the wings and on other parts of the body, including the head.
When the feathers are parted, straw-colored body lice may be seen running rapidly on the skin in search of cover. Eggs are deposited in clusters near the base of small feathers, particularly below the vent, or in young fowls, frequently on the head or throat. Eggs hatch in about a week and lice reach maturity within twenty days.
This is the most common louse infesting grown chickens. When present in large numbers, the skin is irritated greatly and scabs may result, especially below the vent.
The Shaft Louse or small body louse (Menopon gallinae) is similar in appearance to the body louse, but smaller. It has a habit of resting on the body feather shafts of chickens where it may be seen running rapidly toward the body when feathers are parted suddenly. Sometimes as many as a dozen lice may be seen scurrying down a feather shaft.
Since the shaft louse apparently feeds on parts of the feathers, it is found in limited numbers on turkeys, guinea fowl and ducks kept in close association with chickens. It does not infest young birds until they become well feathered.
The same control measures used to eliminate mite populations is effective for treating lice. It is more important to apply the insecticides directly to the bird’s body rather than the premises