3. Head orientation



Types of Head Orientation: There are three types of insect head orientation according to the inclination of the long axis of the head and the position of the mouthparts.

  1. Hypognathous (hypo - below: gnathus - jaw). Eg.: Grass hopper, Cockroach
·         The mouthparts are projecting downwards.
·         The angle between head and the resting body is 90º.
·         This type is also called as orthopteroid type.

  1. Prognathous (pro -in front; gnathus - jaw). Eg.: Beetles.
    • The mouthparts are projecting forward
    • Head is parallel to the body.
    • The angle between the head and the body is 180º.
    • It is also known as coleopteroid type. 
  1. Opisthognathous (opistho - behind; gnathus - jaw). Eg.: Bugs.
    • The mouthparts (proboscis) are projecting backward.
    • Proboscis is held in the fold of the foreleg beneath the body.
    • The angle between the head and the body is 45º.
    • It is also called as opisthorhynchus/ hemipteroid type.

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