The common red mite, Dermanyssus gallinae, is an external parasite of chickens and turkeys. It feeds by sucking blood from its host. They tend to hide by day in crevices within the poultry house and come out at night to feed on the birds. Red mites appear pale grey in colour before they feed, then turn to bright red after feeding, however, they can be almost black in colour when full of blood. Red mites can be seen with the naked eye; being up to 0.7mm in size. If they crawl onto your skin they are irritating and move quite quickly.
Signs
- Presence of grey/red mites up to 0.7mm, around vent of birds and in housing, particularly crevices.
- Birds are often restless due to the irritation.
- May cause anaemia and death in young birds.
- Loss of condition.
- Pale comb and wattles.
- Drop in egg production.
- Blood spots on eggs.
- Staff/owner complaints of itching.
Treatment
There are several separate preparations available for successful treatment, both for the birds and for the housing. Some products work by breaking down the waxy cuticle of the mites exoskeleton (body), which is very resilient.
Where there is a particularly heavy burden the birds may become lethargic and would probably also benefit from some vitamins to get them through the stress of red mite in addition to the mite treatment.
Prevention
Thorough cleaning, fumigation and insecticide treatment between batches are essential to keep mites under control. Where there is a heavy infestation, regular repeat treatments may be necessary.
Good house design to eliminate cracks and crevices to reduce the places mites can hide also helps. Effective monitoring of mite numbers on a regular basis and implementation of control measures before birds are heavily infested improves control.
It must be realised that mites hide during the daylight hours and tend to generally come out at night, so unless you look closely or you have a particularly heavy infestation you may not know they are present. Treatment of birds after dark, although not easy, is the best option as this is when the mites are the most active.
Burning the bedding or moving it well away from the birds for composting are the best ways to reduce mite numbers. Straw bedding gives the mites a place to hide by crawling up the straw shaft; therefore the use of shavings is preferable, particularly when trying to eliminate them.