Psocodea

• Lice


  • Spend their entire lives among the hairs or feathers and are very host specific
  • Ovipositing females glue their eggs (nits) to hairs or feathers
  • They molt several times but undergo minor morphological change in the process (incomplete metamorphosis)
  • The cycle from egg to egg requires several weeks
• Lice: Wings

  • Wingless, flattened insects, usually 2-4 mm long
• Lice: Claws

  • Adapted for clinging to hairs or feathers
• Anoplura


  Blood feeders, mouthpart stylets retracted within the head when not in use
• Order: Mallophaga (biting/chewing lice)

  • Mandible
  • Maxillary palpi
  • Antennae
  • Head
• All bird lice are biting lice
• Bird lice do little damage
• Suborders of Mallophaga

  • Amblycera
  • Ischnocera
• Amblycera

  • Able to move quickly, have tarsi which are longer and modified for clinging to smooth surfaces
• Amblycera

  • Menacanthus stramineus (chicken body louse)
  • Menopon gallinae (shaft louse of poultry)
• Ischnocera


  • Have legs which are fitted for clasping, antennae are longer and project freely
• Order: Anoplura/ Siphinculata (blood/sucking lice)


  • Hematopinidae (short-nosed lice)
  • Linognithidae (long-nosed lice)
• Linognithidae

  • Linognathus setosus (canine sucking louse)
  • Linognathus vituli (long-nosed cattle louse)
  • Solenopotes capillatus (the little blue cattle louse)
  • Polyplax spinulosa (rat sucking louse)
  • Pediculus humanus humanus (human body louse)
• Head lice

  Have three forms: Eggs/Nits, Nymph, Adult
• Head lice: Eggs/Nits

  • Laid by adult female at base of hair shaft nearest scalp
  • Firmly attached to hair shaft, oval-shaped, very small and hard to see
  • Yellow or white in colour
  • Take about 8-9 days to hatch
  • Cemented firmly to hair shaft and can be difficult to remove
  • Likely-to-hatch eggs no more than 1/4 inch or 1 cm from hair shaft base
• Signs and symptoms of head lice infestation

  • Tickling feeling of something moving in the hair
  • Itching, caused by an allergic reaction to the bites
  • Irritability and difficulty sleeping; head lice are most active in the dark
  • Sores on the head caused by scratching, which can become infected
• Mode of transmission for head lice

  • Head-to-head contact is the most common way
  • Shared clothing
• Pets do not play a role in the spread of human lice
• Domestic cattle serve as hosts for 3 species of Anoplura and 1 species of Mallophaga