Amateur
Entomologists'
Society

Insect classification

A photograph of an adult male Small White butterfly, _Pieris rapae_

An adult male Small White butterfly (Pieris rapae), just one of two species of butterfly that are called Cabbage Whites.

People recognise things by giving them a name. This is also true for living things. Common ones have names from everyday language. For example, the Cabbage White Butterfly, or the hoverfly, or the dragonfly, or the ladybird. These names are fine for general everyday use, but they do have problems:-

  1. There are two different types of butterfly that are called the Cabbage White.
  2. There are over 250 different types of hoverfly in Britain.
  3. The name dragonfly refers to a number of different species, not just to one.
  4. In other parts of the World, ladybirds are not called ladybirds. For example, in North America ladybirds are called ladybugs.

There are other problems as well. One of these is that the name can be different in different parts of the country. For example, a woodlouse is called a Jiggy Pig in some parts of the country, and by other names elsewhere. Another problem is that animals that are rarely or never seen won't have an everyday name.

Several hundred years ago, as science was developing, scientists started to name and describe living things in Latin. Often the process became tedious and at times the descriptions became the name! The situation became very chaotic. Eventually, a Swedish scientist called Carl von Linné tried to sort it all out. (The Latin version of his name is Carolus Linnaeus - he lived 1707-1778.) He devised a system using two names. One of these is the species name (in older writings it may be called the trivial name). This species name is more or less unique to that specific type of plant or animal. Also, he wanted his system to show how different things were related. He therefore grouped different species that he thought were related into a genus (plural genera). Hence, each different type was called a species and had two names:-

Genus species

The genus name is written first and begins with a capital letter.
The specific (or species) name is written second. It does not have a capital letter. Sometimes the species is named after someone. In these cases the name may begin with a capital letter.

The words used for the names were generally in Latin, the language of science and learning at the time. To make it stand out, the name was underlined when written. When typesetting a book, the printer will put underlined words into italics. Hence, in a book, the scientific names are in italics.

The Latin for 2 is "bi" (e.g. a bicycle has 2 wheels). A Latin term for name is "nome". If these two words are put together, we have the word "binomial". Hence, the two-name system devised by von Linné became known as the "Binomial naming system".

He tried to show how different genera were related by grouping them into a family. A number of different families were grouped into an order, orders into class, classes into a phylum, and several phyla into kingdoms. The two main kingdoms are the plants and the animals This list of groups (or hierarchy) may be shown as follows:-

This system tries to show how the different types of living things are related, it is called a "Natural System of Classification". He published his ideas in his book "Systema Naturae" in 1735. This was revised a number of times. The tenth edition, published in 1758, is the most important. Modern classification in Zoology is based on this.

Linnaeus was influenced a lot by the earlier writings of the English naturalist John Ray (1627-1705). In fact, much of Linnaeus' work is based on, and is an extension of, Ray's works. This is particularly true of the classification of plants. Linnaeus's ideas on plant classification were published in his work "Species Plantarum", published in 1753.

The Binomial name is followed by the name (or abbreviation) of the person who first described the species. This person is called the author.

The Binomial System is used by scientists all over the world. This means that the names are international. Therefore, if you write an article about Pieris brassicae, all scientists will know what species you are writing about. This would not be true if you wrote about the Cabbage White Butterfly.

Many people are "put off" by the scientific names. This is a shame because they are generally easy and many people use them without realising when they talk about plants. The best way is to use them from the beginning. It doesn't matter if you pronounce them wrongly, eventually you will learn the correct pronunciation. The important thing is to use them. You will probably have trouble at first. Do persevere as you will soon get the hang of them. Then you will wonder why you were wary of them in the first place!

Previous: Overwintering | Next: Insect Groups