Ectoparasites

• Facultative Ectoparasite – intermittent host contact

  Obligatory Ectoparasite– continual host contact
• The Insecta class of parasite has around 30 orders but only 3 are of vet importance.

  1. Flies (Diptera)
  2. Fleas (Siphonaptera)
  3. Lice (Phthiraptera )
• Most insect orders have a similar life cycle. Juvenile = nymph, broadly resembles an adult but the genitalia and wings are not developed. Nymphs make a new cuticle and shed 4 – 5 x, increasing in size to become an adult.
• An insect's pupal stage is the bridge between juvenile and adult. It does not feed and is generally immobile. They are metabolically very active as old larval tissues and organs are lost or remoulded and replaced by adult organs.
• Arthropod ectoparasites include hard and soft-bodied ticks. Ticks are obligate parasites who are blood-feeding. They feed periodically, taking large blood meals and spend a large portion of life spent off host, so habitat is important.
• Ticks are relatively small order of about 800 species but one of the most important arthropods of vet interest. There are two main families.

  1. Ixodidae = hard ticks. Almost all species of vet importance
  2. Argasidae = soft ticks. Small number species of vet importance