This lab focuses on familiarizing students with the respiratory apparatus of different insects. Tracheae are chitinous tubes that branch into fine intercellular tubes called tracheoles to facilitate gas exchange. Spiracles are openings of the tracheal system that can have closing devices and vary in number and position between insect groups. Terrestrial insects typically have at least 8 pairs of spiracles while aquatic larvae may have only 1-2 pairs or none. The diversity of respiratory structures is an important adaptation for insects inhabiting aquatic or terrestrial environments.

1. University of Sulaimania
School of Science
Department of Biology
2nd Class Year
Practical Entomology
2011-2012
12th Lab.
Insects’ Respiratory Apparatus
Lecturer: Farhad A. Khudhur

2. Objective
• This Lab. making the students to be familiar
with different insects respiratory apparatus.
• Students must know more details about the
diversity in respiratory apparatus of aquatic
and terrestrial insects.

3. Respiration
• Tracheae – chitinous tubes
• Tracheoles – fine, intercellular tubes
• Spiracles – openings of tracheae
– With closing device
– Primitively 1 lateral pair/segment
– Sometimes modified
• Piercing
• Telescoping
• “Spiracular gill”
• Body Wall
– Undifferentiated integument
– Tracheal gills

5. Spiracular Distribution
– Polypneustic at least 8 pairs of spiracles (e.g.,
adults of terrestrial insects)
– Oligopneustic – 1-2 pairs of spiracles
• Amphipneustic – 1 pr mesothorax, 1 pair post-
abdominal (e.g., Trichoptera: Psychodidae larvae)
• Metapneustic – 1 pair post-abdominal (e.g.,
Diptera: Culicidae larvae)
• Propneustic – 1 pair mesothorax (e.g., dipterous
pupae)
– Apneustic – no spiracles (e.g.,
Ephemeroptera and odonata larvae)

18. References
• Gillot, Cedric. (2005). Entomology. 3rd ed. Springer,
Dordrecht., The Netherlands. 831 pp.
• Grzimek’s Animal Life Encyclopedia, 2nd edition. Volume 3,
Insects, edited by Michael Hutchins, Arthur V. Evans, Rosser
W. Garrison,
• Resh, Vincent H. & Cardé, Ring T. (2003). Encyclopedia of
Insects. USA. Academic Press, Elsevier Science, 1266 pp.
• Elzinga, Richard J. (1997). Fundamentals of Entomology. 4th
ed. New Jersey, Prentice-Hall, Inc. 475 pp.
• Gullan, P.J. and Cranston, P.S. (). The insects: An Outline of
Entomology. 3rd ed. U.K. Blackwell Publishing Ltd. 505 pp.