Northern Fowl Mite the deadly threat to chickens

northern fowl miteThe northern fowl mite (Ornithonyssus Sylviarum) are extremely small but tenacious creatures that pose a deadly threat to chickens. They can quickly infest an entire flock of hens and, if not treated quickly, they can kill.

How dangerous is northern fowl mite infestation in chickens?

What makes northern fowl mites exceptionally dangerous is that they have a short life cycle. As such, they breed incredibly quickly. As they are so tiny in size, far smaller than the red mite it’s virtually impossible to spot them in small numbers, but within a couple a months you can have several new generations swarming their ranks – up to 20,000 over a 70 day period.

Northern fowl mites live by drinking the blood of the infected chicken, so once a chicken has got a large population of northern fowl mites living on it, it soon becomes anaemic. The mites live and breed on the bird for their entire lifecycle and feed on it constantly.

Where there’s a large infestation they can consume a quarter of a hen’s blood volume in just four days. The resulting anaemia can cause loss of appetite, malaise, weight loss, paling of the comb and reduced egg laying. It will also leave your chicken far more vulnerable to other parasites and infections. The end result for an untreated hen is death.

How to spot northern fowl mite in hens

Northern fowl mites prefer cooler weather, and although they can infect all year round, your flock is most prone during the colder months. Their preferred temperature is around 65°F (17°C). Spotting individual northern fowl mites is difficult because they are so small, however, in larger numbers they are much easier to find. Because the mites spend their entire lives on the chickens, they cover them with their faeces, eggs and dead skin. This causes a greasy discolouring of their feathers which may become matted, especially around the vent area. The greasy layer often prevents the feathers staying waterproof and in the rain the bird can become wet and the feathers sodden and flattened.

Checking the skin near the vent is the place where you’re most likely to see the mites, especially if there are a lot of them. If you do find them and they crawl on your hands or onto your clothing, it’s important not to go near other birds in case you spread the mites around the flock. Wash your clothes and hands immediately and change your clothing before re-entering the coop. Keep any infected birds away from the rest of the flock until they have been thoroughly treated and are clear of the mites.

Images of northern fowl mite are rare, but there’s one over at NC State University which you can see by clicking here

Northern fowl mite treatment

Treatment depends upon how infected the chickens are. There are some off the shelf treatments available if they are not showing symptoms of anaemia and seem generally healthy in themselves. However, mites have become resistant to many of the compounds created to kill them and even if you do, there may still be mites living in the coop and unhatched eggs that have not been killed waiting to re-infect. If in any doubt, we would thoroughly recommend that you seek professional veterinary advice and treatment.

Northern fowl mite prevention

Preventing the mites getting to your chickens or eradicating them before a major infestation takes place is far preferable to treating them once it has happened. To make sure that you undertake proper prevention, you will need to treat not only the entire flock, but also the coop, run, feeders and waterers and any accessories that they have access to. Unlike red mite, they don’t tend to leave a host, so once on a hen, they will stay there for their entire life, however, it only takes one mite to fall off or get knocked off and it could soon find itself waiting for the next hen to come its way.

To help prevent infestation, check your birds weekly for problems and treat them regularly with pyrethrum products or diatomaceous earth to kill off smaller populations quickly.  Because the life cycle of the northern fowl mite is so short, you should retreat infected birds within a week, otherwise you risk eggs hatching and reinfecting. Always remove infected birds away from the flock until treatment is complete and make sure that they are not reintroduced whilst unhatched eggs may still be on their bodies.

Use food grade diatomaceous earth to treat the dust bath, nesting boxes, perches, coop and run. Small amounts can also be used in the feeder. Wash the waterer thoroughly.

In addition, you need to try and prevent animals which can pass on the northern fowl mite getting near your flock. In particular wild birds and rodents. Make sure you clean up any chicken feed which has been spilt in the vicinity of the run and if you have a problem with vermin, set traps. The best way to deal with birds is to get a fully enclosed run.

Have your chickens been affected by northern fowl mite? If so, let us know how you dealt with it. 

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