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Melophagosis
Melophagosis is the infestation of the fleece by a brown, flattened, wingless insect, the size of a grain of wheat, which breeders often call the false louse or, incorrectly, the sheep tick. It is neither a louse nor a tick: it is a fly whi...
What is it?
Melophagosis is the infestation of the fleece by a brown, flattened, wingless insect, the size of a grain of wheat, which breeders often call the false louse or, incorrectly, the sheep tick.
It is neither a louse nor a tick: it is a fly which has lost its wings and which spends its entire life in the wool of the sheep, where it bites the skin to feed on blood.
The infestation is rarely fatal, but it is very uncomfortable: the animals scratch themselves, damage their fleece and misuse their food.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Moderate but constant itching: animals rub themselves, chew their fleece, scratch with their hind legs.
Wool tangled, torn off in patches, soiled with small spots of brown droppings.
Dull and dirty fleece, devalued for sale.
Pulling the wool aside, we see the brown insects running at the base of the strands, and we find dark brown cocoons, the size of a grain, stuck to the fibers.
In heavy infestations: pale mucous membranes due to anemia, weight loss, lambs which grow more slowly.
Restless animals, which graze or eat for less time.
The signs become more pronounced at the end of winter and diminish significantly after mowing.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The parasite carries out its entire cycle on the animal: it does not develop in the ground or in the building.
The female does not lay eggs: she gives birth to an already developed larva, which she sticks to a wool fiber and which transforms into a cocoon before releasing a new insect.
Repeated bites irritate the skin and trigger scratching; it is this scratching that damages the fleece.
In the event of a massive and prolonged infestation, the regular withdrawal of blood ends up causing anemia, especially in young and poorly nourished animals.
Outside the animal, the parasite only survives for a very short time.
Accommodation in buildings during the winter, animals packed together, long wool.
Purchase of animals without quarantine or fleece examination.
Late mowing or no mowing.
Animals that are poorly nourished, young or already weakened by other parasites.
Mixed flocks, loans of rams, gatherings.
No treatment after mowing, when the parasite is easiest to eliminate.
Transmission
By direct contact between animals, in particular from the mother to the lamb and between animals packed together in a sheepfold during the winter.
By freshly contaminated wool and equipment, but the insect, incapable of living for long outside the animal, is transmitted mainly by contact.
By introducing an infested animal into a healthy herd: this is the most common mode of entry.
This insect does not settle on humans, although it can occasionally bite a person handling animals.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The diagnosis is simple and is carried out on the living animal: simply separate the wool at the base of the strands, on the flank, neck and shoulders, and look. The insect is visible to the naked eye.
The veterinarian confirms and above all makes the difference with other causes of itching, first and foremost scabies, whose treatment and health issues are not the same.
It assesses the extent of the infestation on several animals in the group and the general condition of the herd.
In the case of pale mucous membranes, he checks for anemia and at the same time looks for internal parasites, often present in the same animals.
Treatment
External insecticides suitable for sheep, applied to the skin or in a bath, as well as certain injectable antiparasitics, can eliminate the parasite. The choice of product is up to the veterinarian, depending on the season, the length of the wool and the type of production.
Treatment must concern the entire herd at the same time, because the animals recontaminate each other at the slightest contact.
The most effective time is just after shearing: the short wool lets the product reach the skin and the parasite is deprived of its shelter.
As the cycle takes place entirely on the animal, a second pass is often necessary to destroy the insects coming from the cocoons present at the time of the first treatment; the veterinarian fixes the pipe.
No dose or rhythm is improvised, and we never use products intended for other species or homemade preparations, which are dangerous for both the animal and the breeder.
Waiting times for meat and milk differ depending on the product and must be respected without exception.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Quarantine purchased animals and examine their fleece before integrating them into the herd.
Mow regularly and take advantage of this time to treat if necessary.
Avoid crowding animals in buildings and ensure good ventilation.
Monitor the fleece at the end of winter, the period when the infestation is strongest.
Do not share uncleaned mowing equipment between farms.
Maintain good nutritional status: well-fed animals tolerate infestation better.
Possible complications
Anemia in heavily infested animals, particularly lambs.
Stunted growth and reduced performance.
Devalued fleece and skins, stains and persistent defects on leathers.
Scratching wounds can become infected and attract flies in the hot season, with risk of myiasis.
Worsening of the general condition when internal parasitism is added to the external infestation.
When to see a veterinarian
You see brown insects running through the wool, pulling apart the strands.
Many animals scratch and damage their fleece.
Brown cocoons are stuck to the wool fibers.
Animals have pale mucous membranes or lose weight.
Lambs do not gain weight during the winter.
You are hesitating between scabies and false lice: have the veterinarian decide, the treatments and obligations are not the same.
Prognosis
The prognosis is very good: properly treated at the herd level, the infestation disappears.
Anemic animals recover with good nutrition, but severely affected lambs often remain stunted.
Recurrences almost always come from partial treatment or from an animal introduced without quarantine.
Frequently asked questions
Is it a tick?
No, despite the name many breeders give it. It is a wingless fly that lives permanently in wool. Unlike ticks, it does not leave the animal and does not survive long in the external environment.
Should the entire herd be treated?
Yes. Animals become recontaminated at the slightest contact, particularly in sheepfolds in winter. Treating a few animals just shifts the problem.
When is the best time to intervene?
Just after shearing: the short wool allows the product to reach the skin and the parasite loses its shelter. This is also the time when infested animals are most easily spotted.
Can this parasite bite me?
It may occasionally bite a person who handles animals, but it does not settle on humans or reproduce there. Temporary discomfort is possible, nothing more.
References
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
ANSES — Agence nationale de sécurité sanitaire (France)
Content reviewed by the TunisieVet editorial team · Updated 09 August 2026
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