Fundamentals of Entomology

COMPARATIVE ACCOUNT OF INSECT EXTERNAL MORPHOLOGY :HEAD

COMPARATIVE ACCOUNT OF INSECT EXTERNAL MORPHOLOGY

HEAD
The head of an insect is composed of a series of segments, which are specialized for food gathering and manipulation, sensory perception, and neural integration. The head bears the eyes (compound eyes and ocelli), antennae, and mouthparts. The anterior part of the head is the frons. The anterior area below the dorsum of the head, between and behind the eyes is the vertex. The area below the compound eye, on the side of the head, is the gena. The liplike sclerite is the clypeus.

• Based on the inclination of long axis of the head and orientation of mouth parts there are three types of insects heads.
  1. Hypognathous: (Hypo-below ; gnathous-jaw)
  This type is called orthopteroid type. The long axis of the head is vertical, it is at right angles to the long axis of the body. Mouth parts are ventrally placed and project downwards. E.g. grasshopper, cockroach.
  2. Prognathous: (Pro-infront ; ganthous-jaw)
  This type is also called coleopteroid type. The long axis of the head is horizontal. It is in line with the long axis of the body. Mouth parts are directed forward. e.g. ground beetle.
  3. Opisthognathuos: (Opistho-benind; gnathuos-jaw)
  This is also called hemipteroid type or opisthorhynchous type. Head is deflexed. Mouthparts are directed backwards and held in between the forelegs. e.g. stink bug.


Insect vision

Endocrine System