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Lice infestations can affect the general health of sheep and reduce the quantity and quality of wool.

There are three species of lice that infest sheep in New Zealand:

  •     Bovicola ovis (formerly Damalinia ovis) - body or biting louse
  •     Linognathus pedalis - foot louse (sucking)
  •     Linognathus ovillus - face louse (sucking)

Of the three species Bovicola ovis causes the most problems with the two species of sucking lice seldom being of clinical significance.

Lightly infested sheep may show no clinical signs but when lice numbers increase sheep will rub against objects and pull and bite at their wool.  Lice move up and down the wool staple and spread from sheep to sheep with close contact.  Adult lice are about 2mm long, light brown in colour and feed by biting at the skin surface.

Lice are sensitive to light, when detecting lice at least 10 sheep per mob should be examined, 10 to 20 partings per side of the sheep are recommended.