Steven Cheshire's British Butterflies
British Butterflies: Education: Technical terms
Technical Terms and Diagrams
This page contains a list of technical terms which may be mentioned in the species descriptions and elsewhere on this web site.
The suspension of activity during the summer, warm/hot period. A summer version of hibernation. Especially prevalent in species which occur in very hot dry regions.

Butterflies or moths which have two breeding cycles per year.

Hibernation and aestivation.

Two different forms of the same species.

The suspension of activity during the winter, cold period.

The process of dramatic physical change e.g. from a pupae to a butterfly.

A species which only uses one plant species as a larval food plant.

A species which uses several closely related plant species as a larval food plant.

The occurrence of many forms of the same species.

A species which uses host plants from different genera.

Butterflies or moths which have three breeding cycles per year.

Butterflies or moths which have one breeding cycle per year.
Genetics and population
A genetic or environmentally produced/induced variation of wing pattern compared to the usual form of the species.

Any chromosome other than a sex-chromosome.

Rod-like structures present in pairs in every cell of the body.

A gradual change of a character or feature in a species over a geographical area, often as a result of environmental heterogeneity.

Restricted to a particular region. A specialist species which for example, only occurs in one country or region.

A sexual abnormality in which male and female parts develop simultaneously.

An individual in which the two sexes are combined.

Cultural, social, biological, or other differences within a group. Being diverse and not comparable in kind.

A sexual abnormality in which an animal develops first as one sex and later as the other. It is due to an incorrect balance between the male and female-determining genes (see gynandromorph).

The preponderance of blackness - generally referring to variation in wing colouration. Melanistic forms often occur in populations of the White Admiral.

The male reproductive cells.

The X chromosome is a Female sex-determining chromosome. It is a part of the XY sex-determination system. The X chromosome was named for its unique properties by early researchers, which resulted in the naming of its counterpart Y chromosome.

The Y chromosome is a Male sex-determining chromosome. In mammals, it contains the gene SRY, which triggers testis development if present resulting in males. The human Y chromosome is composed of about 60 million base pairs. DNA in the Y chromosome is passed from father to son, thus tracking many surnames. Y-DNA analysis is thus used in family history research.

The Egg (Ova)
The hard, protective outer casing or shell of a butterfly or moth egg (ova).

The tiny opening through the egg shell (Chorion) of a butterfly or moth egg through which the male sperm enters prior to being laid.

The Caterpillar (Larva)
A stage of larval development. Each larval instar occurs when the larva sheds its skin (ecdysis) in order to allow it to grow. Butterfly and Moth larvae have between 3 and 6 larval instars.

The process of skin shedding or moulting of the chitinous cuticle of an insect as it grows. The period between each ecdysis is known as an instar.

Paired openings on the sides of insects through which they breath.

The Chrysalis (Pupa)
A case enclosing and protecting a pupa. Usually formed from silken thread with the inclusion of other materials such as grass or tree bark.

The pupa uses the cremaster to attach itself to silken pads. The cremaster is found at the tip of the abdomen of a pupa and consists of an arrangement of hooks which are entangled in a pad of silk spun by the larva.

The Adult (Imago)
The part of the body of a butterfly or moth behind the thorax. The Abdomen contains the reproductive organs and gut.

The sensory organs projecting from the front of the head of both butterflies and moths. Butterflies tend to have antenna which are club shaped at the end while male moths can have feather-like antenna.

Part of the male genital organs: a pair of modified appendages at the end of the body by which the female is held during copulation.

The area between the eyes of a butterfly.

The structure a female has for laying eggs.

The feeding tube of a butterfly. The proboscis is formed from two cylindrical tubes which fuse after the adult butterfly emerges from its pupae forming a sealed tube through which sugary liquids such as nectar are drunk.

Paired openings on the sides of insects through which they breath.

The middle section of an insects body.
Diagram showing the main anatomical features of a butterfly. Illustration copyright Steven Cheshire
Above: Diagram showing the main anatomical features of a butterfly. Wing shape and venation based on the Large White.
The Adult (Imago) Head
The jaws : present in the larva, atrophied in the imago (adult butterfly).

A pair of short sensory feelers belonging to the mouth-parts and attached below the head.
Illustration Copyright Steven Cheshire
Above: Diagram showing the main anatomical features of a butterflies head and proboscis.
Wing shape, pattern and colour
Anal Angle
The corner of the hind-wing nearest the posterior end of the body (tornus of hind-wing).

Male scent scales for attracting females. The area around these scales found on the upper forewing of butterflies and moths releases a sexual pheromone which attracts females of the same species. The use of pheromone lures is sometimes used to monitor certain moth species which are rarely encountered otherwise.

The tip of the fore or hind-wings, at that end of the costa which is farthest from the body.

Towards the base of the wing, nearest the body.

An area of the wing surrounded by, but not crossed by nervures (veins).

The front (leading) edge of the fore or hind-wings.

The central part of the fore and hind wings, between the basal and postscapula areas.

Humeral Lobe
A projection from the basal part of the costa of the hind-wings. It helps to keep the fore and hind-wings together during flight, by increasing the overlap between them.

Inner Margin
The posterior edge of the fore and hind-wings.

A crescent shaped mark which occurs as part of the wing pattern. Lunules are often present around the marginal parts of a butterflies wing.

Eye-spots which occur on the butterflies wings. Eyes pots are a defence mechanism. Eyes pots may also be present of caterpillars to ward off predators.

The area of the wings between the decal and sub-marginal areas.

The area of the wings immediately inside the marginal areas.

The outer edges of the wings.
 Illustration copyright Steven Cheshire
Above: Diagram showing the main features of the uppers ides of a butterflies wings. Wing shape and venation based on the Large White.