Lice are small, wingless insects that are parasites of birds and mammals. They are usually less than 10 millimetres in length and are rarely seen without the aid of a microscope or magnifying glass. Lice are short lived and usually host specific. Lice can be recognised by the following features:
- Small, flattened body
- Wingless and colourless
- Short, stubby antennae
- Legs with hooked tarsi adapted to gripping their hosts
- Chewing or biting mouthparts (biting lice) or piercing and sucking mouthparts (sucking lice)
A few species of lice have adapted to live and feed on humans, such as the head louse Pediculus capitis, the eggs of which are commonly called nits and the body louse Pediculus humanus.
Lice have relatively short lives of 2-8 weeks depending on the species. The female lays up to 9 eggs per day on the hair or feathers of the host. The nymphs resemble adults and develop through 3 instars before they reach sexual maturity.
Most sucking lice species feed on the blood of the animals they live on while biting lice usually feed on the feathers and skin of their hosts. Haematopinus asini is a common louse found feeding on horses while Linognathus species are common parasites of domestic mammals.
Lice are parasites of almost all birds and mammals and are found throughout Australia where their hosts occur. Some species of lice are restricted to just one host species and will often spend their entire life on only one particular part of the body.