Lice (singular: louse) (order Phthiraptera) are an order of over 3000 species of wingless parasitic insects. They are all obligate ectoparasites of mammals and birds.
The order has traditionally been divided into two suborders; the sucking lice (Anoplura) and chewing lice (Mallophaga), however, recent classifications suggest that the Mallophaga are paraphyletic and four suborders are now recognised:
- Anoplura - sucking lice, including head and pubic lice (see also Pediculosis)
- Rhyncophthirina - parasites of elephants and warthogs
- Ischnocera - avian lice
- Amblycera - chewing lice, a primitive order of lice