Ento 101: Entomology. What? Why?

See Ento.101 page for disclaimers.

The Etymology of Entomology.


Entomology‘ is the study of insects,  and the word is derived from the greek  Entomos meaning, “having a notch or cut (at the waist)”, and logia meaning, “the study of”.  Aristotle (384 BC – 322 BCE) seems to have originated the word, by his observations of the segments that form insect bodies or perhaps due to the sharply defined division between the thorax and abdomen of some insects. If Charles Bonnet would have had his way, this course would be called “Insectology” 101, because the “…barbarous sound…” of the word ‘entomology’ “terryfy’d” him. Bonnet was a Swiss naturalist who suffered from a syndrome (named after himself) that caused him to see complex visual hallucinations, which may have contributed to his fear of the word. But in this course, Entomology 101, we need have no fear…

Entomology as we know it today is technically the study of insects. But even as Aristotle included other segmented animals with jointed legs, such as spiders, scorpions and centipedes in his definition of entomology, so do we also today. In this course I will include arachnids, myriapods and even some terrestrial crustaceans in the Order overviews.

Entomology as a Science

Entomology is a biological science, a branch of Zoology. As in any zoological field, the aim of entomology is the understanding of life. Zoologists want to learn about the origins, evolution, behaviour, and ecology of their subjects. This search for knowledge has created a number of interlinking and specialized fields within the Zoological fold, most of which are applied to entomology.

  • Cell biologists: the study of cells and their functions
  • Ecologists: the study animals and their interactions with their environment and other species
  • Parasitologists: study  parasites
  • Epidemiologists: study the spread of diseases.
  • Ethologists: study behaviour
  • Geneticists: study genetics
  • Developmental biologists: study of development and growth.
  • Physiologists: study physical functions and adaptations
  • Systematists: study evolutionary relationships between living and fossil animals and categorise types.
  • Palaeontologists: find fossils and use them to study evolutionary relationships
  • Taxonomists: discover and describe new species


Currant Fruit Fly

The number of insect species outnumber all other species of life combined. Because of the vast number of insects species known, there is a necessity for even more specializations in many of the above fields.  For instance, a taxonomist may specialize in the Order Diptera (the true flies), but even the known Diptera currently number over 158 000 species, with estimates of about a million true fly species being possible. With numbers like that to deal with a taxonomist may specialize in only one or two families of a total of about 150 Dipteran families.

Why study entomology?

The World Conservation Union. 2010. IUCN Red List of Threatened Species. Summary Statistics for Globally Threatened Species. Table 1: Numbers of threatened species by major groups of organisms (1996–2010).

Estimated Diversity (by number of described species)¹

Besides being a lucrative subject for our ever-present curiosity, why bother studying insects? In regards to diversity, they are the most successful class on the planet, with 28 orders and about  one million species being described. They are important because, except in the oceans, the evolution of insects has been interwoven with the evolution of life on earth for over 400 million years. They function as recyclers of the dead, distributors of seed and pollinators of plants. They provide food for a multitude of life including birds, fish and man. On the other hand, they eat our crops, our forests, infest seeds and spread diseases. They influence our lives directly by feeding on our food, by helping to produce it through pollination, and even by being part of our diet. Some, in life or death, feed on us. With all these interactions, how can we not want to know more about insects?

As the lives of insects intersect ours in so many ways, we have a number of specialist careers that attempt to deal with our interactions. Forestry entomologists study the life cycles of forests pests that can degrade lumber quality and then find means to control them. Agricultural entomologists specialize in crop pests while veterinary entomologists deal with the parasites of livestock and the vectors of livestock diseases. Medical entomology is a major field, which examines the many insects that can affect human health. A field that is gaining in popularity due to the needs of law enforcement agencies is forensic entomology, where the understanding of the life cycles of arthropods that inhabit decaying bodies can contribute vital evidence to crime scene investigations.

In my attempt in an online course in Entomology, I will be largely ignoring these practical applications of entomology. As important as practical entomology is, my concerns are driven by curiosity and a fascination with the lives and forms of the spineless critters that inhabit our Earth.

Next installment in Ento. 101: Who? (A Brief History of Entomology)

Be sure to visit the comments for additional information!

General References:

  • Neil A. Campbell and Jane B. Reece, 2002. Biology (6th edition), Benjamin Cummings, San Francisco.
  • Norman F. Johnson and Charles A. Triplehorn, 2004. Borror and DeLong’s Introduction to the Study of Insects (7th edition), Brooks Cole.
  • Robert L. Dorit, Warren F. Walker Jr., and Robert D. Barnes, 1991. Zoology, Saunders College Publishing, Orlando.
  • William S. Romoser, 1973. The Science of Entomology, Macmillan Publishing Co., Inc., New York.
¹ Estimated number of described species from The World Conservation Union. 2010. IUCN Red List of Threatened Species. Summary Statistics for Globally Threatened Species.
(Last update: 4 December, 2010)
Addendum 01/01/2011
A simple introduction to the career of entomology, with demonstrations of sweeping with a net and the use of a malaise trap. Produced by the Science Alberta Foundation.


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This entry was posted in Diptera, Entomology, Entomology 101, History, Insect and tagged , , , , , , , .


  1. Joan 12 November, 2010 at 8:15 PM #

    About time too. :)This is a brilliant start Adrian. I cannot wait to read the rest.

  2. Kurt 13 November, 2010 at 8:41 PM #

    Great start, Adrian. I’ll be staying tuned for the next installment!

  3. Ted C. MacRae 13 November, 2010 at 10:05 PM #

    Well done, Professor Thysse.

    Of course, insects are merely a clade of crustaceans, so we could say that crustaceans are the most succussful taxon on the planet, and that they have effectively colonized both land and sea!

    • Adrian Thysse 16 November, 2010 at 2:33 PM #

      Please, please…you’re making me blush.

      And next time, raise our hand if you want to speak OK? 😉

  4. Dave 14 November, 2010 at 10:34 AM #

    Hi Adrian,

    Good start. The only comment I would make is don’t give the oceans too short a shrift. Insects haven’t taken over the oceans as they have the land, but then neither have their more formally crustacean relatives done especially well on dry land. Isopods sure, and a few amphipods, crabs, and ostracods, but colour me unimpressed.

    The intertidal has a pretty good insect fauna. Well, mostly flies and a few beetles, but there is at least one book called ‘Marine Insects’ with a dated overview. There are marine caddisflies that live in rock pools on the New Zealand coast and oviposit in starfish (e.g. Philanisus plebeius). Also there is the water strider genus Halobates with species that are marine. Maybe some future lecture can address why there are relatively few marine insects.



  5. Adrian Thysse 16 November, 2010 at 2:37 PM #

    Thanks Dave. I would like to look into the saline side more, and, perhaps (if it does not require any understanding of physics or chemistry!), I may add a section to the syllabus.

  6. BioBob 4 December, 2010 at 11:55 AM #

    An excellent introduction!

    I would add some kind of qualification to the statement “most successful taxon on the planet” eg “multicellular taxon” or “among the most” since perhaps bacteria, plants, etc could be argued as well and the superlative is not really required to make your point.

    You might reference the fact that ‘Insects provide demonstrations of virtually all evolutionary and biological concepts in a human accessible scale, both temporal and spatial’ as a reason why insects could be studied or are important.

  7. Adrian Thysse 4 December, 2010 at 4:28 PM #

    Thanks BioBob! I have re-written the ‘taxon’ sentence,and I believe it makes more sense now. As this is a learning project for me I will look into insects as convenient subjects for the study of evolution when I get to that part of the syllabus.

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