The lowdown and dirty on Red Mites…
Red mites (Dermanyssus gallinae) are blood-feeding ectoparasite’s. They have a waxy exoskeleton that provides protection & helps to make them a formidably resistant pest. They can apparently, travel 100’s of metre’s in a night and can lay dormant in a dis-used coop for months to even years until a suitable poultry host arrives once more.
They tend to live in small cracks inside poultry houses, mostly as close to the birds as they can get. This means the favourite spots for colonisation areas include perch ends and nest boxes. Places where the birds rest and sleep for prolonged periods of time. They are nocturnal and come out at night for a blood feed generally from chickens and turkeys during the warmer months. Once the temperatures increase and are consistent, the populations can explode rapidly.
They are difficult to eradicate and have significant welfare and egg production implications for commercial and backyard bird owners alike.
Red mites are not species-specific and will feed on any type of bird, although ducks and geese are not normally affected because they do not roost as such, and are relatively active, moving around their house at night. They will also bite humans if they can get under your watch strap!. Wild birds and sparrows visiting your coop can bring these pests to your hens.
An infestation of red mites (also called chicken mites, roost mites or poultry mites) will cause skin irritation, stress and a rapid reduction in egg numbers. In extreme cases (usually the birds that roost on the ends of the perch rails near the colony), birds will become anemic due to the repeated blood loss and will often eventually die.
They are particularly resilient. In the wild, red mites will live inside bark cracks of trees, waiting for long periods of time between feeds until a bird roosts nearby.
Although mites usually spend the day hidden in cracks, only going onto birds at night for an hour or so to feed, a few can sometimes remain on a bird if infestation rates are high. Generally though, you will not find red mites present on birds when examined through the daytime. This can falsely lead the poultry keeper to think they do not have a mite problem.
Life Cycle of a Red Mite
The complete life cycle is shortest during hot, humid weather. A typical cycle during the height of summer is only 7-10 days long.
A blood feed takes 1 to 2 hours and usually takes place at night when birds are roosting & sleepy.
- Eggs hatch into 6 legged Larvae in 2-3 days. They do not feed.
- Larvae moult into 8 legged Proto-nymphs in 1-2 days and start to feed.
- Proto-nymphs will have a blood feed and turn into Deuto-nymphs in another 1-2 days
- Deuto-nymphs turn into adult red mites in 2-3 days and continue to take blood feeds
- After feeding a female red mite will mate and within 1-2 days is laying eggs.
- Females will routinely take a blood feed. Males feed less frequently.
- The cycle is of course repeated and numbers increase…
Important to note:
- Temperature: the speed of the red mite life cycle depends on temperature and humidity. Red mite are inactive and cannot reproduce below 9°C so are usually only a problem for us between October and May in the Southern hemisphere. If the weather is repeatedly warm day after day, the life cycle can be reduced to as little as 5 days.
How to check in Chook house for red mite
Here’s how to check & recognise if your chicken house has a red mite problem:
- Firstly you need to don your head torch and head out after dark. Look for colonies of red mites and their excreta (looks like cigarette ash) close to where birds roost at night. Check perch ends for evidence. It is a great idea if perches are removable, this makes it easier to find them and treat them. Sometimes when collecting the eggs from the nest box, the eggs will have mites crawling on them. You may notice red ‘blood spots’ (actually squashed mites) on the eggs & perch rails.
- After dark, red mites will be active, crawling out and along perches to get to their hosts for a blood feed. Using a torch, look for mites crawling along perches and walls of housing. Wipe the underside of the perch with a white tissue and look for smears of blood.
- Birds will be restless and you will be able to hear and see this as you get near to the coop. The birds will not be resting quietly, but instead shuffling about and preening feathers trying to remove the red mites that are biting. They may not want to go in their house to roost at dusk or indeed may roost outside in trees or on the ground.
- The birds will be seen to be dust bathing a lot, this is their only way to try and deter the mites from crawling through their feathers.
- Egg production will usually decrease and eventually birds will stop laying. They may lay outside or on the floor of the coop because they get bitten whilst sitting in nest boxes. Egg yolks can be pale.
- Birds will start to lose condition. As the infestation gets worse, they are losing a lot of blood. They will have a pale comb and wattles. They will become anemic and eventually they will die. Birds at the bottom of the pecking order are often forced to roost near the worst infestation so are often the first to die.
Red Mite Treatments
This is where things get messy! There are more treatments for red mite than you can shake a stick at!. We have tried many of these in our time with our own poultry flocks, looking for the magic remedy…often we thought we had found it, only to have resistant mites appear the next year, making us scramble for something else to try.
The problem being mites are clever and only a certain number die when a chemical treatment is used. 5-10% of mites and often the eggs, remain viable, only to hatch happily the next year. This problem is also due to coop setups and configurations. ( see the section on ‘Setting up a mite resistant coop system’ as this discusses setups in detail including the choice of materials etc ).
Generally store bought – chemical treatments, are not overly user or environmentally friendly. They have to be quite gritty to work against the mites.
Steam or water blasting can help to remove faecal material from the coop and dust. A common fail with this method is more to do with the coops setup. The mites and eggs remain hidden between tight nooks and crannies, able to repopulate once more.
Blow Torches – great for killing adult mites and most likely eggs if you can get to every little nook and cranny in the coop. This is normally impossible but you will achieve some reduction in numbers for a period of time as long as you don’t burn down the coop!
Creosote – active ingredient in Creosote was banned in 2003 as found to be carcinogenic. It is still available in commercial preparations but not for retail consumers.
Paraffin/Kerosene/Diesel/White spirit – All used by old poultry fanciers at times. Not overly environmentally friendly but does kill back adults & possibly eggs.
Jeyes Fluid – apparently this glasshouse disinfectant has been noted to be poisonous to poultry!.
Neem oil – Reduces insect feeding, acts as a repellent and interferes with insect hormone systems. Banned in the UK due to organ effects in humans.
Spot-on Products– Dog spot on preparations are chemicals and therefore have not been trialed for use in poultry. Chemicals used around poultry, must be shown to not cause residues that may enter the food chain eg Eggs or meat.
Exzolt -There is a new (end of 2017) commercial product from MSD Animal Health called Exzolt. This is different to other commercial products because it is added to the drinking water. The active ingredient is called fluralaner and this is absorbed by the gut and enters the bird’s bloodstream. It attacks the female mite’s nervous system and causes the mite to die after a blood feed.
Exzolt is administered twice, 7 days apart so that it treats two mite life cycles and trials have shown a 99% kill rate. There is no egg withdrawal period and there is a short 14 day withdrawal for meat.
It is currently only available in commercial sizes and the dosing needs to be accurate according to the weight of the bird so mixed flocks of bantams and large fowl would need separating. Add to this that it is only available on prescription from a vet, it is still out of reach for most of us with back garden poultry but might be of interest if you are a breeder with large numbers. ( Note: this is still a chemical compound being ingested by your poultry. It is not addressing red mite eggs and has no deterrent effect on further red mite colonization )
Natural powders such as Diatomaceous earth are fabulous against adult mites as long as they walk through the powder. They have no effect on eggs or mites that do not walk through the powder of course. To be effective the powder needs to be in situ at all times when mites are traveling. Remember it is always a good idea when using any powder to wear a mask and not to use it when the chickens are in the coop as they are susceptible to dusts with their intricate respiratory systems.. Dust of any shape or form is irritant to the airways of both the chook’s & ourselves when used in a confined space.
Flea powders contain ‘Permethrin’ generally. Its use has been banned in Canada as it is thought that it may pose a risk to aquatic organisms, bees and beneficial insects and birds.
There are numerous disinfectants and detergents available also. These aim to dissolve the waxy exoskeleton of the mite causing disruption and death. The problem being the resistant mite eggs are again hidden away, surviving and hatching another day to continue the colonization.
Management factors are an important part of mite control. Exposing these ‘hidden’ areas is important and not making these areas in the first place when setting up/building or selecting your coop is even better! this is where Mite resistant coops are superior as they basically have less cracks & crevices for mites to live and breed in.