Image: Louse


Louse, line drawing.

Andrew Howells
© Australian Museum


Lice belong to the Order Phthiraptera.

What do lice look like?

  • 0.5 mm - 10 mm in length but most are shorter than 5 mm.
  • Ovoid or the abdomen is swollen making it look like a lopsided dumb-bell.
  • Flattened as if pressed from above.
  • Body appears hard.
  • Very short; sometimes held in a groove hence often difficult to see.
  • Thread-like, or club-like; never longer than head.
  • Very small or absent.
  • For chewing or munching, or a pointed tube for piercing and sucking.
  • Absent.
  • Six legs.
  • Have modified hook-like claws for clinging to feathers or fur.
Abdomen tip:
  • Cerci (tails) absent.

Where are lice found?

  • On mammals and birds clinging to hairs or feathers.
  • Often restricted to one host and usually favour one specific part of the host's body.

What do lice do?

  • They are external parasites and are often found groups around food source.
  • When disturbed they may run but generally they cling to hair or feathers.
  • They feed on feathers, hairs, skin flakes and blood. Some will feed on eggs of other lice species.
  • They are active day and night.

What looks similar?

  • Psocids can be distinguished from lice by their long thread-like antennae, and ovoid body. They also do not occur as external parasites, but may accidentally crawl on birds or mammals.
  • Fleas can be distinguished from lice as they are flattened from the sides and jump when disturbed

Last Updated: