VPA 221: Veterinary Entomology and Acarology (1+1)

THORAX - INSECTA

• Has three segments
  • Prothorax
  • Mesothorax
  • Metathorax
• These  segments may be distinct and separate or may be fused together.
• Appendages on the thorax include
  • Legs- a pair, one for each segment
  • Wings

Legs

• Consist of basal coxa by which the  leg is attached to the body, followed by trochanter, femur, tibia and tarsus.
• Tarsus is usually five jointed.
• Last tarsal segment is provided with a pair of claws.
• Below each claw a pad like structure called pulvilli is seen.
• Between the claws a sensory pad like structure or spine/bristle like structure called empodium /arolium can be seen.

Wings

• Normally two pairs-on meso and meta thorax
•  In Diptera the posterior pair is reduced to a pair of balancers or halteres
• Wings are supported by veins or breathing tubes (trachea) which give rise to the wing venation.  Identification of insects is based on wing venation.  The veins are named as costa, sub costa and 6 longitudinal veins. Refer the textbooks for other methods of naming wing venation