There are several types of biting lice that effect chickens and other poultry. These are known as ectoparasites or external parasites as they live on the outside of the bird.

Lice range in size from about 1 to 4mm and can be found crawling on the bird at the base of the feathers, spreading from bird to bird by direct contact. Clumps of eggs are usually found at the base of the feathers below the vent.

Off the bird lice can survive for a few days so although less likely, can also spread from bird to bird via the hen house or litter. Most chickens will have a few lice on them from time to time and won't be particularly bothered by them but it's important not to let the numbers get out of control or they will be causing severe irritation and feather loss as they over groom.

On chickens it is usually Menopon gallinae which is a yellowish colour flat louse about 2mm long. They are fast moving - if you part the feathers you can see them run for cover amongst feather shafts. Waterfowl usually suffer with shaft lice Holomenopen spp which are dark, thin lice. They are longer around 5mm but again soon dash for cover when exposed. They can be found on feathers close to the shaft as well as on skin. Due to their colour, they are quite hard to spot on dark coloured birds.

The Signs of Lice

The photo to the right shows lice eggs attached to the base of a feather, found below the vet. Often, they can be confused with a slightly messy bottom. They are very hard to remove and if there are a lot of them, it's often easier to kill the lice using drops of Ivermectin as detailed below under 'Treating Lice'.

• 1 to 4mm fast moving lice at the base of the feathers.
• Lice eggs stuck to the feather shafts below the vent.
• A drop in the number of eggs laid.
• Irritation, scratching.
• Over preaning, feather loss, red, bare bottoms.

Preventing Lice

Avoid contact with birds that have lice, provide a to help chickens and other poultry rid themselves of lice. Diatomaceous Earth can be added to the dust bath which will help.

Treating Lice

Ivermectin is by far the easiest way to remove lice, and also kills most common poultry worms, however it is unlicensed for use on poultry so you should only use it under the guidance of your Vet. Ivermectin is available online (details on our Ivermectin page in the Medcication section) in drops that are put onto the skin at weekly intervals or as your vet advises for 3 weeks. The eggs can hatch up to 3 weeks later so ensure you treat at this point, even if there don't appear to be any more lice as the eggs will hatch. Ivermectin has a residual effect that is useful.

Powders containing the Pyrethrium are also effective however most are not licensed to be used on birds themselves so again, you should be applying these at the instruction of your vet.

Some organic powders contain tea tree and other ingredients that the lice don't like. Diatomaceous Earth like diatom can be effective with a few regular treatments each week over a couple of weeks, this works by drying the lice up but getting the bird dusted all over can be difficult. It is sometimes useful to add these powders to nesting areas, bedding and into dust baths (in the case of chickens, turkeys and guinea fowl) so that birds can effectively apply these themselves.

The life cycle of biting lice is around 3 weeks - so it is important when using a product to remove them that you re-check regularly and re-treat as necessary after a week as most products will not kill the eggs and these will hatch over this period.