Chicken louse

The chicken louse (Goniodes dissimilis) is a tiny insect belonging to the order Mallophaga, family Philopteridae. It is a wingless parasite that lives exclusively on the skin and feathers of birds.

The adult insect has a flattened body, 1.5 to 2.5 mm long, with a yellowish-brown coloration that makes it difficult to spot among the bird's feathers.

The pest has a wide head equipped with powerful chewing mouthparts adapted for feeding on skin scales, feather fragments, and dried blood.

These insects possess three pairs of sturdy legs with claws, allowing them to cling firmly to the feather shafts and move across the host's body.

The life cycle of the chicken louse involves incomplete metamorphosis, with all stages (egg, nymph, adult) occurring directly on the bird, ensuring rapid population growth.

The primary hosts for Goniodes dissimilis are domestic chickens, although the parasite can also affect other types of poultry.

This pest is an ectoparasite that causes a condition known as mallophagosis, leading to significant economic losses in the poultry industry.

The infestation causes severe itching, forcing birds to constantly groom themselves, pull out their feathers, and self-mutilate.

In cases of heavy infestation, egg production drops, growth in young birds is stunted, and the overall immune system weakens, leaving the poultry vulnerable to secondary infections.

The damage also includes a decrease in the market value of the carcasses and the quality of feather down, which is a major concern for large-scale farms.

The chicken louse is active throughout the year because the environment inside a poultry house and the body temperature of the birds provide ideal conditions for reproduction.

The highest parasite population levels are typically observed during the colder months when birds are housed in crowded indoor conditions with poor ventilation.

Warm and humid conditions within the coop accelerate the incubation period of the louse eggs, leading to rapid surges in the infestation levels.

During the summer months, with regular access to outdoor runs and sunbathing, the intensity of the infestation may decrease, but it never fully disappears.

Lack of sanitation and irregular coop disinfection allows the pest to remain active across many generations throughout the year.

The first sign of infestation is restless behavior: chickens frequently shake themselves, preen excessively with their beaks, and show clear signs of agitation.

During a physical inspection, clusters of adult insects or their eggs (nits) can be found on the skin, particularly around the vent, under the wings, and on the neck.

The feathers of an infested bird become ruffled, dull, and brittle, with patches of baldness appearing due to constant picking.

• Dark spots on feathers, which are parasite excrement.
• Inflammation, redness, and scratching marks on the bird's skin.
• Reduced weight and loss of appetite in the flock.

If not addressed promptly, chickens can become severely emaciated, which often leads to the death of weakened individuals.

Controlling the chicken louse requires a comprehensive approach, including the treatment of the birds and the deep disinfection of all equipment and housing structures.

Modern insecticidal products in the form of powders, sprays, or drops are used on the birds' skin according to the manufacturer's instructions.

It is crucial to repeat the treatment after 10–14 days to eliminate new insects that hatch from eggs, as insecticides are generally less effective against the egg stage.

Providing dust baths with a mix of ash and sand is a highly effective preventative measure, as it allows birds to naturally clean their plumage of parasites.

Maintaining strict hygiene, regular bedding replacement, and preventing contact between domestic poultry and wild birds are essential strategies for protecting the flock.