Aaaaargh… it’s red mite!

Judging by the number of calls we receive on the subject, this is one of the most common problems domestic chicken keepers face. This is peak time for the
red mite season as they, just like us, are at their most active in the warmer weather.

These tiny parasitic mites, Dermanyssus gallinae, to give them their Latin name, are known as red mite and are about 1mm long. They are referred to as a ‘temporary parasite’ as they do not actually live on the chickens, spending the majority of their lifecycle hiding in small nooks and crannies in the henhouse.

Finding that red mites have set up home in your henhouse is not a sign of bad husbandry as they are very common in the general environment, especially in the warmer summer months. In fact they can be spread by wild birds and/or by hitching a ride on new hens you may introduce to your established mite-free flock. There are also anecdotal stories of mites arriving on shop-bought bedding, although I have not seen any evidence of this myself. The fact is that no matter how thorough your cleaning regime, at some point you will almost certainly find yourself host to this tiny and bothersome mite, so do take comfort from the fact that there is little you could do to prevent it.

Get in tune

Red mite is not always easy to spot; some keepers are not even aware they have it until it becomes an infestation, but you can become attuned to the signs of its arrival and then take quick and appropriate action.

Until they have fed, the mites are actually a pale grey colour, and are hard to spot as they like to hide during the day and come out to feed after dark, attracted to the heat given off by the hens’ bodies. All nooks or crannies within the henhouse will make an ideal spot to hide away, so areas such as underneath the perches and dropping boards should be checked every few days. Owners of plastic moulded henhouses seem to suffer fewer problems as there are less hiding places, and houses usually come apart easily allowing for deep cleaning and pressure washing.

Traditional wooden houses offer greater opportunity to hide away, and a useful tip can be to insert a piece of white paper into those hard-to-reach cracks and crevices. If the paper comes out with blood smears or little brown dots that produce blood when squashed with your finger, then you can be sure you have mites in your house. Another indicator can be tiny red spots on the eggs, which can occur when mites are living in the nest box material, and get squashed while the egg is being laid.

The symptoms

The birds themselves will also show symptoms and behaviour associated with mites and the loss of blood which occurs as the parasites feed on them. This can manifest as weight loss together with an increase in feed consumption, as well as a general lethargy. In heavy infestations a paler comb will illustrate the loss of blood as the number of mites increase.

When mites are in residence in large numbers, the birds may be unwilling to go in to the house to roost at night, which often leaves unaware keepers at a loss as to why they are exhibiting this new and strange behaviour. In one particularly severe case, I was told of a keeper who opened her henhouse at night and shone in a torch, to see her hens literally covered in tiny red mites – it was no wonder they were not happy to roost there.

The lifecycle

The breeding cycle from egg to mature breeding adult is just seven days, which is why mite numbers can build so quickly if left untreated. This rapid cycle, plus their nocturnal habit, ability to hide and their presence in the general environment is what makes red mite such a difficult foe. Treatment and prevention needs to be ongoing and it is worth getting into the mind-set of routine maintenance to keep numbers at a controllable level. Eradicating red mites is not a case of waging a war in which the foe will be vanquished with a single treatment of chemical warfare.

Effective treatments… for the henhouse

Fortunately, there are a number of treatments available, and because of the rapid breeding cycle and concerns over the build-up of resistance to chemical treatments, some exciting new products are just becoming available to domestic keepers.

Liquid spray treatments are particularly useful as they allow you to apply the product into all those hard to reach corners, and are available in ready to use spray bottles, or the more economical concentrates which you dilute with water and use a sprayer to apply.

Poultry Shield is perhaps the best known and is very safe to use for you and your hens as it works by dissolving the mites’ protective waxy outer coating, leading to desiccation and death. It needs to be re-applied at least weekly to break the cycle as it will kill the adults while leaving the eggs to hatch.

D-Mite is a recent introduction to the market and is silica based, and works as a barrier rather than on the mite itself and leads to their starvation. It creates a slippery surface which prevents the mites from moving around the house and means they cannot reach the hens to feed. Again, it is not chemical based so is completely safe to use.

These liquid spray treatments are great for getting into those hard-to-reach areas that mites love to hide in, but I advise making life really tough for them by delivering a double-whammy and using powder based treatments too.

Diatomaceous (pronounced die-a-toe-may-shus) earth has many uses, but for the chicken keeper it works as a very effective drying agent that kills mites by desiccation. Available under many different brand names, all are based on the fossilised remains of microscopic silicone-shelled animals that died millions of years ago. It feels like an extremely fine powder which leaves your hands feeling incredibly dry. The sharp edges of these silica fragments work as an abrasive on the waxy shell, which leads to them losing moisture and drying out within around three days. As with the sprays, it works as a physical barrier so there is no danger of chemical residues and it is completely safe to use for humans and animals, and being a dry powder, it can be sprinkled freely into the bedding and nesting material.

… for the hens

As I have already stated, the mites do usually not live on the hens themselves, but with powder based anti-mite products it is an idea to also apply regularly to the hens, paying particular attention to the vent area, nape of the neck and under the wings. Application can be made simpler by holding the hen securely by both legs, and supporting her as you turn her upside down, which will cause her to naturally expose the underneath of the wings ready for application.

One of the newest treatments becoming available to home users are predatory mites. Available online from the ChickenVet website, they work by feeding on the red mite. At first it may feel strange to introduce one mite to deal with another, but these predators are not as hardy as the red mite and die of starvation within seven days of the red mite being consumed. Predatory mites are only effective if used in a house which has not had any other form of treatment for at least four weeks previously, and need to be used within three days of arriving by post. Early feedback from users suggests they are an effective addition to the red mite treatment range, and useful in that they are completely harmless to both the chickens and humans.

As with any aspect of your hens’ health, prevention is better than cure, and regardless of whether there is any indication of red mite, I recommend a weekly clean out of the coop, which includes removal of all the bedding, dropping boards, and perches and a generous dust of mite powder whenever the temperature rises above 5ºC (41ºF), and then include other specific mite treatments at the first sign of any mite activity.

While red mite is a common problem, it is one that it is easy to control, if not, perhaps, to eradicate, and as long as you remain vigilant for the signs and have the tools ready to respond quickly, your hens will remain in perfect health. It is only when you ignore the problem that red mite, with their amazing ability to reproduce so quickly, will become a problem.

Find out more about the British Hen Welfare Trust at www.bhwt.org.uk