How to control parasites in your poultry flock

Parasites such as red mite and worms enjoy the warm, moist surroundings and although summer 2007 was colder than expected, it was mild enough to encourage their rapid growth in poultry houses.


The red mite (Dermanyssus gallinae), an exo-parasite, is the cause of increasing problems in the poultry industry, particularly with free-range layers.

The optimal environment for commercial layers is also ideal for the rapid reproduction of the red mite.

What to look out for?

The adult red mite is 1-2mm long. And mites that have not fed tend to be white, cream or grey in colour, only becoming red after a blood meal. Others will appear dark red to black after the blood is digested, says David Parsons, of The Poultry Health Centre.

After a blood meal, the female lays up to seven eggs in a crack or crevice. And under ideal conditions, the life cycle of the mite is complete within five to seven days.

poultry flock

Red mites do not like the light and seeks out dark places within the poultry house where they can spend most of their time. The lighting levels in conventional houses often mean that a layer of dust covering a nest box will block out enough light to provide a home for the mites, he says.

The mites blood-feeds for 1-2 hours per night and during the day they hide in cracks and crevices of the poultry sheds.

The adult red mite can survive up to nine months without a blood meal, says Mr Parsons.

They are blood suckers and remain dormant for sometime adds Michael Clark, Partner of Minster Veterinary Practice.

Top five tips on avoiding red mites:

1: In terms of layers you can’t rear them without red mites, it’s a matter of control, says Mr Clark. Try to ensure that there isn’t an environment for red mite. Aim to reduce the mite at turnaround time and don’t allow them to disappear into the nooks and crannies of the poultry shed, he says.

2: People only tend to notice them when there is a serious problem. Red mites in laying hens causes egg withdrawal. So check for their presence at least once a week, he says.

3: Use damp blotting paper to check around the nesting boxes and if it comes back blood streaked, then you have red mites, advises Mr Clark.

4: Red mite has resistance to certain products and disinfectants. Use a product that is licensed and one that will reduce red mites, he says.

5: However, don’t just rely on the product alone, after use, go back to the shed with blotting paper and check areas around nesting boxes again for blood streaks, to be sure that the red mites are dead, says Mr Clark.


Performance losses are caused by worm infestations (endo-parasite), particularly in free-range layers.

What to look out for:

Sara Perez of the Minster Veterinary Surgery, York, says that intestinal worms can cause inflammation of the gut (enteritis), and this leads to poor absorption of nutrients.

The immune reaction to the presence of parasites also causes the release of chemical mediators that drive weight loss and muscle resorption.

Overall the signs are loss of bodyweight, unevenness in the flock, diarrhoea, anaemia, increases cannibalism through vent pecking due to straining and in more severe cases, death, she says.

Enteritis and weight loss can lead to poor egg quality and even decreases in egg production. It is not uncommon to find pale soft eggshells, pale yolks or smaller egg size in birds infested by worms, says Ms Perez.

It’s advisable to control the infestation of worms before the first clinical signs appear. By the time diarrhoea or enteritis is noticed, the adult worms are already in the intestine of the birds and the moist damaging lesions have already been produced, so the egg production of the whole house could be affected, she says.

Top five tips on avoiding intestinal worms

1: Ideally, worm every eight weeks with Frubenvet that can be used as an infeed wormer or Solubenol, says Mr Clark. Both contain flubendazole which controls the spread of worms and interrupts the life cycle in such a way that minimal numbers of worms are produced.

2: However, if it’s an organic flock you can submit dropping samples to a laboratory every eight weeks, to see what the samples show, says Mr Clark.

3: Thorough cleaning and disinfection of the poultry sheds is necessary to reduce and eliminate worm eggs that may be present in the slats and scratch area. Poultry units that have a history of re-occurrence of worm infestation should be wormed at shorter intervals, according to Ms Perez.

4: Stocking density will have an effect on the infestation, as less birds per sq m means that the infestation will spread more slowly, she says. Worm eggs will also be less able to survive in dry well-drained soil in sunny areas. Rotation of the area of the range available to the birds will also help.

5: Staff, vehicles and tools can transmit egg worms, so strict biosecurity should be maintained at all times, she says.

Intestinal worm treatments:

Flubendazole in feed (Flubenvet) is medicated into the feed and therefore saves on labour as it doesn’t have to be administered in the farm. However, in cases where immediate treatment is required this would not be convenient as the flock would have to wait for the next feed to be medicated. A course of treatment is seven days.

Flubendazole in water (Solubenol) is treated via the drinking water and allows for immediate treatment of the birds when worms are detected and therefore provides a quicker recovery. A course of treatment lasts seven days.

Red mite treatments:

Use a licensed product, but ideally keep checking areas around nest boxes after use by using damp blotting paper and look out for blood streaks.

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