Mites, Lice and Scaly Leg: Controlling External Parasites in Ghana Poultry Houses

A layer farmer at Millennium City brought us a complaint we hear at least twice a month: the birds were on a good layer mash, vaccinated, no deaths, and yet production had slipped from 88% to 71% over six weeks. The combs were pale. Feed intake was down slightly. She had been told it was "stress" and had bought vitamins. We asked a single question: had she gone into the house with a torch at night and looked under the cage rails? She had not. When she did, the undersides of the feeder troughs were crawling with grey and red specks that moved away from the light. Red mite. Her hens were being bled every night, and the mites were hiding in the metal joints every day.

External parasites do not announce themselves the way Newcastle or Gumboro do. There is no sudden mortality, no green diarrhoea, nothing that makes a farmer reach for the phone. Instead there is a slow loss of blood, feathers, sleep and eggs, and because the birds look "fine" the cause is missed for months. On a 2,000-bird layer farm a 15% drop in lay for two months is roughly 18,000 eggs. The mites cost far more than the chemical to kill them.

Know your enemy: the four parasites that matter in Ghana

Farmers tend to say "lice" for anything small that crawls on a chicken, but the four common parasites behave very differently and a treatment that works for one can be useless against another. The single most important distinction is where the parasite lives: on the bird all the time, or in the house and only on the bird at night.

Red mite (Dermanyssus gallinae). The most damaging poultry parasite in the world and very common in Ghanaian layer houses. It does not live on the bird. It hides by day in cracks, cage joints, under feeder lips, in nest boxes and in the ends of perches, and comes out at night to feed on blood for an hour or two before returning to the crack to digest and lay eggs. A red mite is about 0.7 to 1 mm long; grey when hungry, red or dark red when full of blood. In warm conditions (and Ghana is always warm enough) the life cycle from egg to adult takes as little as seven days, so a small population becomes millions within a couple of months. Red mites can survive up to eight or nine months in an empty house without feeding, which is why a new flock in an old house is often infested within weeks.

Northern fowl mite (Ornithonyssus sylviarum). Looks similar but lives on the bird permanently, concentrated around the vent, under the tail and on the fluff below the vent. The feathers there become dirty grey-black with mite droppings, eggs and shed skins, and the skin underneath is scabby and thickened. Because it lives on the bird, treating the bird is what matters most.

Lice. Several species; the shaft louse and the body louse are the ones farmers usually see. Lice are larger than mites (2 to 3 mm), straw-coloured, flat, and fast-moving through the feathers. They do not suck blood; they chew feathers and skin scales, which irritates the bird constantly. Look for clusters of white eggs (nits) cemented to the base of feathers around the vent and under the wings. Lice spend their whole life on the bird and die within a few days off it.

Scaly leg mite (Knemidocoptes mutans). A microscopic burrowing mite that tunnels under the scales of the legs and feet. The scales lift, crust and thicken until the leg looks like it is coated in dry cement. Untreated, birds become lame, lose toes and stop laying. It is slow, it spreads by direct contact, and it is common in local and backyard flocks and in older layers.

Orientation only. Confirm the parasite and the treatment product with your veterinarian, use only products approved for poultry, and observe the egg and meat withdrawal periods on the label.

Signs the flock is being eaten alive

The signs are subtle and they overlap with other problems, which is why we always tell farmers to look for the parasite itself rather than guess from the flock. Still, this pattern should make you suspicious:

• Pale combs and wattles in birds that are eating a proper ration. Red mite anaemia is the commonest cause of pale combs in Ghanaian layers.
• A gradual, unexplained drop in lay of 10 to 25%, often with more cracked and dirty eggs and small blood spots on the shells (crushed mites).
• Birds restless at night, moving around, refusing to use nest boxes, or laying on the floor. Red mite bites in the nest drive hens out.
• Feather pecking and scratching; birds preening excessively; a dusty, scurfy look to the feathers.
• Dirty, matted, blackened feathers below the vent (northern fowl mite).
• Crusty, lifted, greyish scales on the legs, sometimes bleeding where the bird has picked at them (scaly leg).
• Workers complaining of itchy bites on their arms after collecting eggs. Red mite bites people too, and this complaint alone is worth a torch inspection.

How to inspect properly

Inspecting for red mite is a night job. Go into the house two to three hours after dark with a good torch. Run a finger, or a folded piece of white paper, along the underside of the feeder trough, the joints where cage sections meet, the ends of perches and the corners of nest boxes. Crushed mites leave red smears on the paper. In a heavy infestation you will see grey dust that moves, and clusters like ash in the corners. Cardboard traps work well for monitoring: roll a piece of corrugated cardboard into a tube, tie it to a perch or cage rail overnight, and unroll it in the morning. If mites are present they will have crawled into the corrugations.

For the other three parasites, catch birds in daylight. Take a sample of at least ten birds from different points in the house. Turn each bird over, part the feathers around the vent and look at the skin and the base of the feathers for moving mites, lice or nit clusters. Then look at the legs, comparing them with a young, healthy bird if you are unsure what normal smooth scales look like. Ten minutes with ten birds every fortnight is all the surveillance most farms need.

Treating the house: the part most farmers skip

Because red mite lives in the house, spraying birds alone is a waste of money. Farmers do it, see improvement for a week, and then the survivors in the cracks re-infest. A proper house treatment is a sequence, not a single spray.

1. Clean first. Remove litter, manure belts or manure under cages, egg trays, loose boards and anything that can be carried outside. Mites and their eggs sit in dust and manure; chemicals cannot reach them there. Scrape and brush cage joints and perch ends. On a deep-litter farm this means a full litter change, which you should tie in with the flock cycle where possible. See our litter management guide.
2. Wash where you can. A pressure washer or hose with detergent on cages and concrete removes the grease and dust layer that protects mites from spray.
3. Spray an approved acaricide into every crack, joint and hollow tube, not just onto surfaces. Products used in Ghana are typically based on synthetic pyrethroids (cypermethrin, deltamethrin) or organophosphates, and some newer products use silica-based dusts or plant oils. Follow the label dilution exactly; under-dosing breeds resistance. Spray with the birds out of the house if at all possible, or with them removed to one side while the other side is treated and dried.
4. Repeat in seven days. No spray kills eggs reliably. The second application catches the mites that hatched after the first. A third round a week later is wise in a heavy infestation.
5. Treat the surroundings. Spray the outside of the house walls, the roof edge, and stacked equipment. Burn or bury removed litter away from the house; do not pile it next to the wall where mites crawl straight back in.
6. Consider inert dusts. Diatomaceous earth or similar silica dusts, applied dry into cracks and along rails after the spray has dried, work mechanically by drying out mites and do not lose effectiveness through resistance. They are a useful long-term barrier in cage houses.

For an empty house between flocks, the job is easier and much more effective: strip, wash, spray, dust, and leave the house closed for as long as you can. Heat helps; a closed house in the dry season reaches temperatures that shorten mite survival. Our guide to poultry biosecurity covers the full turnaround routine.

Treating the birds

For northern fowl mite and lice, treating the birds is the main job, and for red mite it is the finishing step after the house is done. Options, all to be confirmed with your vet:

• Dusting powders containing a pyrethroid or a plant-derived active, worked into the feathers around the vent, under the wings and along the back. Effective for lice and northern fowl mite. Repeat in seven to ten days for the eggs that hatch.
• Sprays applied to the vent region and under the wings with the bird held upside down, in the cool of the evening. Do not soak birds in the hot afternoon.
• Spot-on and in-water products exist in some markets, including a macrocyclic lactone (ivermectin) used off-label by some vets. These are prescription decisions with real withdrawal implications for eggs; do not self-prescribe.
• Dust baths for floor birds: a shallow tray of dry sand or wood ash mixed with a little sulphur or diatomaceous earth lets birds treat themselves. This is management, not a cure, but it cuts lice and northern fowl mite pressure noticeably.

For scaly leg mite the treatment is local and patient. Soak the legs in warm soapy water to soften the crust, dry them, then coat the whole leg and foot in petroleum jelly, vegetable oil or a proprietary scaly-leg preparation. The oil suffocates the mites under the scales. Repeat every three or four days for at least three weeks, because the mite life cycle is long. Never pull the raised scales off; they bleed and the bird can get a secondary infection. Old, heavily crusted birds may never regrow normal scales and are candidates for culling.

A mini case: lice on point-of-lay pullets

In early 2025 a farmer in Kasoa bought 500 Isa Brown pullets at 17 weeks and called us at 20 weeks because the birds "had not started laying and were pecking each other". When we looked, every bird had lice; the nit clusters around the vents were the size of rice grains. The rearing farm had never treated. We advised him to dust every bird individually, working through the house in the evening over two days, and to repeat ten days later. He also put dust baths of sand and wood ash in the pen and dimmed the lights to stop pecking. Lay started within the week after the first dusting and reached 60% by 23 weeks. The lesson he took away was to inspect pullets on the truck; the lesson we would add is that an itchy, irritated pullet is a pullet that comes into lay late.

Keeping them out for good

Parasites arrive on new birds, on used equipment, on egg trays that came back from the market, on wild birds nesting in the roof, and on people who have been in another poultry house. Prevention is therefore about routine, not one big effort:

• Inspect and treat every batch of new pullets before they enter the house.
• Never bring used cages, nest boxes or egg trays onto the farm without washing and spraying them first. Plastic trays that go to market and come back are a classic red mite route; keep a separate set for the farm.
• Keep wild birds out: mesh the eaves and gaps, and remove any nests you find in the roof space. Sparrows and pigeons carry mites and lice.
• Put cardboard traps in the house every two weeks and write down what you find. A count that goes from zero to a few dozen is your cue to spray before it reaches thousands.
• Give floor birds a permanent dust bath.
• Spray the empty house between every flock, whether you saw mites or not.
• Handle a sample of ten birds every fortnight and check vents and legs. Add it to the same routine you use to check body weight and crop fill.

Combine this with a proper worming programme on veterinary advice, since a bird already weakened by worms suffers more from mites; see deworming poultry.

Frequently asked questions