Red Mites (Dermanyssus gallinae)

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Red mites, also known as poultry red mites, chicken mites or blood mites (Dermanyssus gallinae), are small blood-feeding mites that parasitise birds, especially chickens and other poultry. They are a serious problem in both backyard flocks and commercial poultry production. Red mites may also infest wild birds and, in rare cases, bite humans. Heavy infestations can cause severe stress, anaemia and even death in chickens.

This article explains how to identify red mites, where and when they occur, and how to prevent and control them effectively under UK conditions.

Identification of Red Mites

What do red mites look like?

Red mites have several distinctive features:

  • Size: About 0.6–1 mm long

  • Shape: Flat, oval bodies with eight legs (they are arachnids, not insects)

  • Colour: Grey or pale when unfed, turning red or dark brown after feeding on blood

  • Behaviour: Very fast-moving and mainly active at night

Red mites do not live permanently on chickens. During the day they hide in cracks, joints and crevices, emerging at night to feed on the birds.

Habitat and Conditions

Where do red mites thrive?

Red mites prefer dark, warm and humid environments, particularly where birds are housed. They are commonly found:

  • In hen houses and nesting boxes

  • Under perches, floorboards and loose timber

  • In cracks, joints and crevices of wooden structures

  • In bird nests, both domestic and wild

  • In egg-handling equipment and transport systems in commercial units

They spread easily between flocks via equipment, clothing, egg trays, crates and the movement of birds.

Signs of Infestation

How can red mite infestations be detected?

Common signs include:

  • Red or dark smears on eggs or inside nest boxes (crushed mites or droppings)

  • Chickens appearing restless at night, refusing to roost or excessive scratching

  • Reduced egg production, weight loss and general poor condition

  • Pale combs and legs, indicating anaemia

  • Deaths among young, weak or heavily infested birds

Inspecting the coop at night often reveals red mites crawling on birds and surfaces. A simple test is to wipe a white cloth along perches or cracks – red streaks indicate blood-fed mites.

Life Cycle

What is the life cycle of the red mite?

Red mites have an extremely rapid life cycle:

  • Development from egg to adult can take 7–10 days at temperatures of 20–25 °C

  • Females can lay up to 300 eggs during their lifetime

  • Eggs are laid in cracks, joints and dark hiding places

  • Adult mites can survive up to 8 months without feeding, making eradication difficult

Populations can increase explosively during warm summer months or in heated poultry houses.

Prevention

How can red mite infestations be prevented?

Prevention should be part of routine poultry management:

  • Clean hen houses thoroughly and regularly

  • Limewash walls and treat cracks to reduce hiding places

  • Replace and wash nesting material frequently

  • Apply diatomaceous earth (food-grade) to cracks and under perches

  • Use smooth, mite-resistant materials such as plastic instead of rough wood

  • Quarantine new birds before introducing them to the flock

  • Prevent wild birds from accessing poultry housing

Control Measures

How can red mites be controlled?

Effective control usually requires a combination of methods.

Mechanical cleaning

  • Empty the hen house completely

  • Clean thoroughly using hot water or a pressure washer

  • Allow the structure to dry fully, as mites dislike dry conditions

Heat treatment

  • Red mites die at temperatures above 50–60 °C

  • Use a heat gun or gas torch carefully on cracks and joints

  • Always take precautions to avoid fire risk

Diatomaceous earth

  • A fine powder that dehydrates mites

  • Can be used preventively and during infestations

  • Apply in nest boxes, under perches and in cracks

Biological control

  • Predatory mites (such as Androlaelaps casalis) may be used

  • Most suitable for professional or larger poultry operations

Chemical control

  • Use only products approved for poultry in the UK

  • Always follow label instructions carefully

  • Chemical treatments should be a last resort due to resistance risks

  • Never treat birds directly unless advised by a veterinarian

Occurrence in the UK

Where in the UK are red mites most common?

Red mites are found throughout the UK but are especially common:

  • In backyard and hobby poultry setups with infrequent deep cleaning

  • In small-scale farms using older buildings

  • During warm summers and in heated poultry housing year-round

Red mites are difficult to eliminate completely, but with consistent hygiene, preventive measures and early intervention, populations can be kept under control.

Important: Red mites reproduce rapidly and can survive for long periods without feeding. Ongoing monitoring and prevention are essential. A clean, dry and well-maintained hen house remains the most effective defence against infestation.