Insect Classification And Taxonomy 101: Complete Guide

Insect classification can look complicated, in ordinary English not everybody uses the same names for the same insects.

For instance Slaters, Cheesybugs and Woodlice are all different names for the same animal, in different parts of the world.

This is why insect classification is so important. A scientist called Carl Linnaeus suggested in the 1750’s that an international way of naming things should be set up, so that scientists all over the world could understand each other better.

The science of naming things is called taxonomy and though it can become quite complicated, the basics are easy to understand.

On this page, we will examine things from the particular perspective of insect taxonomy.

How Insect Classification Works

All the living things are divided into a series of sets and subsets, depending on how closely related they are. For instance all living things are divided into 5 kingdoms

• Plants
• Fungi
• Animals
• very small things called Chromista
• other very small things called Protista
• even smaller things called Bacteria
• other even smaller things called Archaea

These last two are so small you can’t see them without a microscope.

Now let’s zoom down into insect taxonomy specifically and look at exactly how insects are classified.

The living members of the kingdom Animalia are divided into approximately 33 smaller groups called phyla singular phylum.

One of which, the Arthropoda is of particular interest to us. This phylum contains the hard shelled, jointed legged animals and is further divided into four smaller groups called Subphyla – or in some classification schemes Classes.

They are:

• Crustacea: things like prawns, crabs and woodlice;
• Myriapoda: centipedes, millipedes and the like;
• Chelicerata: (Arachnida), spiders, scorpions and harvestmen, etc.
• Uniramia (Insecta): things like beetles, bees and flies.

Now the uniramia or class insecta are divided into 28 even smaller, though still pretty large groups called Orders such as:

• Diptera, Flies;
• Coleoptera, Beetles;
• Phasmida, Stick-Insects;
• Dictyoptera, Cockroaches and Praying Mantids;
• Hymenoptera, Wasps, Ants and Bees
• Lepidoptera, Butterflies and Moths;
• and lots lots more.

After this we have Families. Within the order Lepidoptera there are about 90 families. Within each family are a number of Genera and within each genus are a number of Species.

For instance, the common European butterfly known as Small Tortoiseshell is is a member of all the following sets:

• Kingdom = Animalia
• Phylum = Arthropoda
• Class = Uniramia (Insecta)
• Order = Lepidoptera
• Family = Nymphalidae
• Genus = Aglais
• Species = urticae

You should note that most animals and plants are known only by their genus and species names, i.e. the small tortoiseshell is Aglais urticae. Note also that while the genus name is spelt with a capital letter, the species name is normally spelt with a small letter. In printed text the pair are normally written in italics, the rest usually remains unsaid.

You should also note that though an animal will generally share its genus, family, order and class names etc. with other animals, its combination genus/species name will be unique to it.

In some books you may find a person’s name or part of a person’s name written after the animal’s name, i.e. Euclida glyphica (Linnaeus, 1758).

This mean that Linnaeus was the first person to name this moth and that he did so in a work published in 1758. The brackets around his name mean that the species has since been moved to another genus. Linnaeus, being the first person to use this system widely, put a lot of moths in one genus (such as Noctua) and later taxonomists realised that some of them belonged to different genera and moved them – like putting them in a different box.

This means that the species was named and described by Linnaeus, but the genus was described later be a different taxonomist. This process is called taxonomic revision. Also you will occasionally see some species written in a shortened form, e.g., Formica exsecta Nyl., Nyl stands for Nylander and the date is omitted.

I personally do not like this, but people do use it. However it is not much use, if the reader doesn’t know what Nyl. or Hb. stands for and the relevant publication date.

The Class Insecta

Insect taxonomy and classification can, and in fact does, get extremely complicated. With a large number of people discussing the merits of various taxonomic schemes. The one I have followed here and throughout these pages is adapted from that used by the online database Catalogue of Life – and is a basically functional, if not extremely up to date system.

However at the moment, it is important to realise that the greatest use of insect taxonomy is in the facilitation of communication between workers in similar areas – and that the differences between various schemes are fairly unimportant until you know enough to contribute to the argument.

A basic understanding of the relationships between various groups of insects can be gained from any basic taxonomic setting.

The 29 insect orders are numbered in an approximate series of evolutionary complexity, with the oldest and most primitive groups being listed first. They are further classified together into a number of groups depending on their degree of relatedness.

The first four orders are known as the Apterygote orders because all the adults are wingless. Like the immature stages these have no true metamorphosis and are the most primitive insects alive today.

The other 25 orders are called the Pterygote orders because we believe they all evolved from winged forms, even those like the Siphonaptera (Fleas) which are all wingless now.

These are divided up into 16 Exopterygote orders, which have an incomplete metamorphosis (i.e. no pupal stage) and develop their wings outside of their main body; and the Endopterygote orders, which undergo a complete metamorphosis including a pupal stage and have their wings develop inside the body (which are therefore not visible until the adult insect emerges from the pupa).

Key to the Orders of Insects

The Insect Orders

The Apterygota (Wingless insects with no true metamorphosis at all)

Taxonomic Name	Common Name	Number Worldwide	Number in the UK	Number in Australia
Thysanura	3 Pronged Bristletails	55	9	25
Diplura	2 Pronged Bristletails	600	11	32
Protura	Proturans	10	17	30
Collembola	Springtails	3000	300	400

The Exopterygota (Hemimetabolous insects with incomplete metamorphosis

Taxonomic Name	Common Name	Number Worldwide	Number in the UK	Number in Australia
Ephemeroptera	May flies	2000	36	124
Odonata	Dragon Flies	5000	43	248
Plecoptera	Stone Flies	1700	34	248
Grylloblatodea	Ice Bugs	16	0	0
Orthoptera	Grasshoppers	20000	33	1513
Phasmida	Stick Bugs	3000	3	133
Dermaptera	Earwigs	1200	5	60
Embioptera	Web Spinners	300	0	65
Dictyoptera	Roaches and Mantids	6000	4	520
Isoptera	Termites	1900	0	182
Zoraptera	Zoraptera	22	0	0
Psocoptera	Book and Bark Lice	2000	68	120
Mallophaga	Biting Lice	2800	225	186
Siphunculata	Sucking Lice	300	61	22
Hemiptera	True Bugs	100000	1410	3661
Thysanoptera	Thrips	500	180	287

The Endopterygota (Holometabolous insects with complete metamorphosis)

Taxonomic Name	Common Name	Number Worldwide	Number in the UK	Number in Australia
Neuroptera	Lacewings	4700	60	412
Mecoptera	Scorpion Flies	400	4	20
Siphonaptera	Fleas	1400	53	68
Coleoptera	Beetles	370000	3700	19219
Strepsiptera	Stylops	370	16	9
Diptera	True Flies	100000	5700	6256
Lepidoptera	Moths and Butterflies	150000	2400	11221
Trichoptera	Caddis flies	5000	188	260
Hymenoptera	Ants Bees and Wasps	120,000 +		6700

If you still in search of more glorious taxonomic information, don’t forget to check out our page on Entomology Text Books.