Poultry: Ecto-Parasites (External)

by Carole Youngs

Ecto-Parasites - Parasites that affect skin, feathers and scales.

Everything you ever wanted to know about itchy-scratchy parasites on chickens … but were afraid to ask!

Firstly, Prevention is Better than Cure!

Introducing new chickens to the flock

  • Remember that new birds will be ‘naïve’ – meaning they have no acquired resistance – to all the diseases that can affect chickens, so try to ensure they go onto clean ground that has not recently had chickens on it
  • Alternatively, or additionally, use a ground sanitising powder on a weekly basis
  • Keep a very close watch for any signs of illness (eg. loose droppings, ‘raspy’ breathing) and investigate any problems immediately

Housing

speckled-sussex-in-run-2012Your choice of house is important to protect your hens from infestations of pests and parasites. Try to choose one that doesn’t provide lots of nooks and crannies where they can hide (eg. under felt roofs, between tongue and groove boarding, and any awkward joints that you can’t brush out). There are many new types of housing that are designed to minimise these problems, including those made from re-cycled plastic, or with smooth contours.

Ventilation

Always ensure good airflow at the top of the house; this will prevent moist conditions developing, which are ideal for pests and parasites.

Cleaning and Disinfecting

Establish a regular routine, for example: daily ‘skipping-out’ of poo; a weekly application of disinfectant (eg. Stalosan); a monthly clear out of dirty bedding and replenishment; and a twice-yearly ‘Spring & Autumn Clean’, which can include a wash-down with a pressure washer if you have access to one.

Exclusion of wildlife

Most of the parasites that affect domestic poultry will be brought in by wildlife, so take what practical measures you can to exclude them from your chicken coop: place feedstuffs under cover if you can, feed early in the day and only put out as much as the hens will eat so there are no ‘leftovers’; if practical, exclude wild birds by putting netting over the poultry run; use a scarecrow – but move it frequently as birds will get used to it and lose any fear!

Treatment

Whenever you treat your birds for any parasite infestation, or clean out the chicken house, always wear protective clothing: rubber gloves, facemask and overalls.

Poultry Parasites

Red Mite (Dermanyssus Gallinae)

dermanyssus-gallinaeRed mites are most active at night, when they will crawl out of nooks and crannies where they hide during the day, and head for your chickens whose blood they feed on. Not only does this cause intense irritation to the chooks, but also, if the infestation is heavy, they can suck enough blood to make them seriously anaemic. In commercial hen houses, these pests can cause injurious feather pecking amongst groups of hens, which can have a significant impact on productivity.

  • Red mites will normally be active between the months of March to November, though they can be active during a mild winter.
  • During the daytime check the ends of perches, joints and between tongue-and-groove in wooden houses; if present, you’ll see clusters of tiny mites (approximately the size of a pin-head). These may be dull grey in colour, to deep red, indicating they have recently had a good feed from your hens!
  • Affected birds will be dull and fidgety, their combs may be pale and they may go off lay at a time you would expect them to be laying.
  • If you visit the hen house at night with a torch, you may see active red mites both on the chickens (check vent area and under their wings).
  • The sooner in the year you start a control programme, the better you will be able to manage the mites and keep your birds free of infestation.
  • Firstly, clean the chickens’ house: remove and burn all bedding, thoroughly vacuum every nook and cranny, and use a disinfectant designed for the purpose – if you have a pressure-washer, all the better!
  • There are numerous products available, including:
    ORGANIC – including ‘Predator Mite’, which feeds on the red mite without affecting the birds (but don’t use at the same time as any chemical treatment as these will also kill the ‘good’ mites); diatomataceous earth, which is sprinkled over all the areas where mites hide.
    Interestingly, Defra funded a research project in 2008 to test the efficacy of a range of plant-derived products to be used against red mite (specifically for use in large-scale organic poultry houses); the best-performing herb was Thyme as an essential oil, which was effective against mites for up to 15 days and had no apparent injurious effect on the chickens. However, we’re not aware of any subsequent commercial use following the research.  
    CHEMICAL – too numerous to mention, you will find a wide range at any country supplies store. Use these with care, as they can damage aquatic life, and, if not used according to the manufacturers’ instructions and the mites receive a sub-lethal dose, they will in time become resistant to the chemical.
    BARRIER/PHYSICAL – head lice in humans are treated with a liquid that makes it impossible for the mites to crawl on, and this is now available in a spray designed for use in the hen coop.
  • You’ll have to keep repeating the treatments (as directed on the packaging) frequently throughout the season to keep your nice clean house free of the red scourge – but your chickens will thank you for your efforts!
  • And finally, The Moredun Institute are currently leading a project to develop a poultry vaccine to control red mite, research so far has indicated that it’s a “feasible option, and work is progressing well”!

Chicken Lice (Menopon Gallinae)

menopon-gallinaeAs lice live on the chickens (feeding on dead skin and feather debris) throughout their life cycle, they aren’t bothered by cold weather, and will reproduce throughout the year, causing irritation to their host.

  • To check whether this is a problem in your flock, pick up one of the hens and gently part the feathers (on the back and under the wings) to expose the skin; you’ll see lice as small 1-3mm yellowish-grey insects which will scurry away from the light.
  • Next, look around the vent area, where if mites are present, you’ll find their eggs (‘nits’) in clumps at the base of the feathers.
  • To treat, use louse powder all over the bird, parting the feathers as you go. This most usually contains Pyrethrum – a natural insecticide derived from a daisy-type chrysanthemum, it causes death to insects by disabling their nervous system, but is harmless to birds and humans.
  • Treat all birds in the house at the same time, and repeat weekly for at least 4 weeks as their breeding cycle, from egg to adult, is 3 weeks.
  • An alternative, organic, treatment is to use diatomaceous earth, applied to the chickens in the same way as louse powder, or added to a dust bath.
  • If you continue to have problems, your vet can prescribe an Ivermectin based treatment (eg. Frontline) that you apply to the back of the bird’s neck, but do be aware that this product is not licensed for use in poultry, and you will need to discard eggs for the duration of treatment (minimum 7 days).
  • Once you have cleared up the infestation, provide your hens with a dust bath, which will enable them to keep free from external parasites naturally, and enjoy the process at the same time!

The following parasites are known as “Depluming Mites”, as their activities cause loss of feathers and leg scales (which are modified feathers)

Northern Fowl Mite (Ornithonyssus Sylviarum)

ornithonyssus-sylviarumThese mites feed on blood, and although they are present at all times of year, you are likely to have the most severe infestations during the cooler months, with few cases occurring during the summer. They cause intense irritation, anaemia and stress to affected birds, will reduce egg-laying and the hens will lose condition. They may also annoy their handlers!

  • Inspect the hen under a bright light, and use a magnifying glass if you have one. Part the feathers and look around the hen’s vent, tail, back and legs for soiled feathers: blackened, ‘greasy’ looking feathers caused by mite eggs, cast skins, blood and excrement are characteristic of this mite and you may also see scabby areas around the vent.
  • The Northern Fowl Mite spends its entire life cycle on the bird; it reproduces rapidly, and its entire life cycle can be completed in a week under favourable conditions.
  • The mite reproduces rapidly and in intensive conditions a single bird may be infested by as many as 20,000 mites.
  • Mites tend to infest a bird once it reaches sexual maturity at around 20 weeks, but older birds are less likely to support a large population of mites.
  • ornithonyssus-sylviarum-copyright-BioMed-Central-LtdBirds will go off their food, become weak and often appear to be very thirsty. If they have a very heavy infestation can become anaemic.
  • Initially, wash the bird in warm water using a mild baby shampoo, rinse thoroughly and gently dry with a hair-dryer. This will remove most of the mites and their debris.
  • You can then use a pyrethrum powder all over the bird.
  • If you continue to have problems, your vet can prescribe an Ivermectin based treatment (eg. Frontline) that you apply to the back of the bird’s neck, but do be aware that this product is not licensed for use in poultry, and you will need to discard eggs for the duration of treatment (minimum 7 days).

Depluming Mite (Knemidocoptes Gallinae)

Thankfully this is one of the rarer pests, but the action of the mites on an affected chicken will cause sufficient pain to make the bird pluck out its own feathers, hence the name of the mite.

  • Signs to look out for are birds loosing feathers outside of the moulting season; birds pecking at their own feathers; tatty hens and crusty skin.
  • You’re most likely to see this pest in the Spring and Summer months.
  • The mites will burrow under the skin, making most proprietary mite treatments ineffective.
  • This mite’s lifecycle is completed in about 2-3 weeks so repeated treatments are advised.
  • An Ivermectin treatment is recommended, which you can obtain from your vet; as this product is not licensed for use in poultry, and you will need to discard eggs for the duration of treatment (minimum 7 days).

Scaly Leg Mite (Knemidocoptes Mutans)

scaly-leg-mite-copyright-myredhen-co-ukUnfortunately, the damage is likely to be done by the time you realise your chickens are playing host to this irritating pest, which completes its entire life cycle on the bird. This sarcoptic mite is related to the mange mite, and has a similar, intensely irritating effect on its host: the female burrows into the tissue under the scales of the legs to lay her eggs causing exudation, encrustation and raised leg scales. In bad cases the chicken can become very lame. The mite spends its entire life on the bird.

  • It may help to gently wash the feet and legs in warm soapy water, using a soft toothbrush to soften the scales before treatment.
  • Surgical spirit is an old-fashioned remedy, but in many cases will make the legs very sore, so is not recommended.
  • A simple treatment on less-serious cases is to rub a little Vaseline onto the affected legs – this will suffocate the mites, help soothe sore legs and soften the scales.
  • Never try to pull the raised scales off, this would cause the legs to bleed and be be very painful for the chicken.
  • There are proprietary sprays for leg mites (eg. Barrier Health Scaly Leg, and Net-Tex Just for Legs).
  • scaly-leg-mite-copyright-backyardchickens-comDue to the short life-cycle of the mite, repeated treatments are required to ensure that newly-hatched mites are killed as well as the adults – treat on a weekly basis for at least 4 weeks.
  • In very serious cases, your vet can prescribe an Ivermectin spray, but you will need to discard all eggs during treatment and for some time afterwards.
  • Remember that scales are formed in the same way as feathers, and they will not be renewed until the chicken goes through its annual moult, when new scales will replace the old, damaged ones.

And finally, a parasite that is attracted to faeces-stained fleece, fur and feathers:

Fly-Strike

This is NOT a common problem in a well-kept, clean poultry house. However, in a warm spring and early summer any chicken with a dirty back-end, especially one that is debilitated by old age or illness, is vulnerable to fly-strike. Broody hens can also be vulnerable. The culprit is a ‘bluebottle’ fly, which will lay its eggs on the hen’s dirty feathers, the eggs then hatch into maggots, which start to burrow into the hen’s flesh, and creating toxins which, if left untreated, will quickly kill the bird.

  • Always keep the henhouse scrupulously clean in the warmer months; flies are attracted to muck, dirt and smells.
  • If one of your chickens is affected, immediately clean the affected area, picking out any maggots (not nice, but think of the chicken!).
  • If the skin is badly damaged, apply an emollient/anti-bacterial ointment.
  • You may need to separate the affected hen, as the other chickens may start to peck at any wound.

 


 

If you have any favourite ways of effectively discouraging pests, or remedies for established infestation, please This email address is being protected from spambots. You need JavaScript enabled to view it.

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