Dragonflies and damselflies are complex organisms, and there are many specialised and unfamiliar terms used to describe their biology, life and behaviour.
The glossary below may be help to explain the meaning of many of the terms found on this site or other reference materials.
Rather confusingly sometimes, there may be several terms in common usage that describe a single thing. Regardless of scientific nomenclature – the term that refers to how scientists name things – I’ve tried to use the commonly used terms throughout the site and linked to this glossary to describe any alternative names in use.
| Term | Definition |
|---|---|
| Abdomen | Posterior part of body, consisting of ten Segments and ending with appendages. The ‘tail’ of a dragonfly. |
| Anal Appendages, Cerci | Variable size projections from the last Segment of the Abdomen. There are superior (upper) and inferior (lower) appendages. Males use them to clasp the female around the head (dragonflies) or the Pronotum (damselflies) during mating and when in Tandem, and in some species during egg laying. |
| Anal Loop | Distinct group of cells in the hind wing base of Anisopteran dragonflies; its shape can be Diagnostic. |
| Andromorph, Homeomorph | A female with colouring similar to that of a male. Antonym: Heteromorph |
| Anisopteran | Relating to the suborder of true Dragonflies (Anisoptera). Anisoptera means ‘unequal wings’, referring to the larger hind wing of Dragonflies. |
| Antehumeral Stripes | Stripes on the dorsal surface of the Thorax. Usually pale in colour. |
| Anterior | Towards the front, e.g. the leading edge of the wing. Antonym: Posterior. |
| Apex, Apical | At or towards the tip. e.g. that part of a wing that is furthest from the Thorax. Antonym: Basal. |
| Term | Definition |
|---|---|
| Caudal | Relating to the tail, e.g. caudal lamellae are situated at the rear of a damselfly’s body. |
| Caudal Lamellae | Three fan-like structures situated at the end of the Abdomen in damselfly Larvae, used as respiratory and swimming organs. |
| Cercus | See Anal Appendages. Plural: Cerci. |
| Clypeus | The lower part of the face, below the Frons. |
| Costa | Thick vein along the entire leading edge of the wings. |
| Coxa | The segment of leg that connects it to the Thorax (‘hip’). Plural: Coxae. |
| Conspecific | Belonging to the same species. |
| Crepuscular | Species that are active at dusk (often also active at dawn and during daytime in dense forest), such as the Brown Hawker – Aeshna grandis. |
| Cuticle | The tough, waterproof, protective outer layer made of chitin, which covers the body of insects and many other arthropod invertebrates. |
| Term | Definition |
|---|---|
| Diagnostic | A distinguishing feature that confirms an identification. |
| Diapause | Period of suspended growth or development in the egg or larval stages that typically occurs during winter. Diapause enables species to survive unfavourable conditions, development continues with the onset of spring. |
| Dimorphic | Having two distinct forms, especially when this relates to colour. |
| Dorsal | Upper surface of a body. Antonym: Ventral. |
| Term | Definition |
|---|---|
| Ecdysis | The periodic moulting of the 'skin' of a Larva, enabling growth. Marks the end of one Stadia and the beginning of the next. |
| Emergence | The process of a Larva leaving the water and shedding its skin, before drying out and hardening, and eventually flying off as an immature adult. |
| Endophytic | The method of Ovipositing by injecting eggs into plant tissue. See also Epiphytic & Exophytic. |
| Epiphytic | The method of Ovipositing eggs onto the surface of plant tissue. See also Endophytic & Exophytic. |
| Estivation | Laying dormant during summer. See also Hibernation. |
| Exophytic | The method of Ovipositing by dropping or laying eggs into water. See also Endophytic & Epiphytic. |
| Exuvia | The skin shed by Larvae. Plural: Exuviae. |
| Term | Definition |
|---|---|
| Femur | The long leg segment above the ‘knee’ (‘thigh’). Plural: Femora |
| Form | Discrete alternative appearance of individuals within populations, especially in female colouration. See also Polymorphic. |
| Frons | The dorsal part of face. The ‘forehead’ of a dragonfly. |
| Term | Definition |
|---|---|
| Hawking | Flying back and forth over an area searching for prey. Characteristic of some larger dragonflies. |
| Hemimetabolous | A mode of development of certain insects, which in Odonata is comprised of three distinct stages: the egg, Naiad, and the adult (Imago). These stages go through gradual devlopment changes; there is no final pupal stage. Also called incomplete metamorphosis. |
| Heteromorph | Typical colouration of a female, differing from the male, usually duller. Antonym: Andromorph |
| Hibernation | Laying dormant during winter. See also Estivation. |
| Humeral Stripes | Dark stripes on the humeral suture of the Thorax. Useful in identifying damselflies. |
| Hyaline | Clear or transparent (especially with respect to wings). |
| Term | Definition |
|---|---|
| Jizz | The general appearance and first impressions that one obtains of a species in the field. |
| Term | Definition |
|---|---|
| Labium or Mask | Lower lip-like structure covering the mandibles on the underside of the head. In Odonate Larvae it is very large and specialised, and used to catch prey. |
| Labrum | Lower portion of face, upper lip-like structure shielding the mandibles from the front. |
| Larva | Alternative (but less accurate) term commonly used for the Naiad, the stage of Odonate life which is spent underwater prior to Emergence, and lasting up to several years dependant on climate and species. Plural: Larvae. Odonata larvae are also commonly known as Nymphs. |
| Lateral | Relating to the side of an object. Antonym: Medial. |
| Term | Definition |
|---|---|
| Naiad | The immature aquatic stage of Hemimetabolous insects (Ephemeroptera, Odonata and Plecoptera), which differs greatly from the adult in both habitat and form. Commonly called a Larva or Nymph. |
| Node | A noticeable ‘notch’ of the Costa, roughly midway between base and Pterostigma. Thought to make the wing more flexible, significant during hovering. |
| Nymph | Common term used for Naiad, especially in dragonflies and damselflies. |
| Term | Definition |
|---|---|
| Occipital Triangle | Triangular area on the dorsal surface of the back of head (Occiput) lying between the eyes in Anisoptera (except Gomphidae). |
| Occiput | The area of the head behind the eyes. |
| Ocellus | A simple eye made up of a single lens. In Odonata, three of these lie between and/or in front of the compound eyes. Plural: Ocelli. |
| Odonate | A member of the insect order Odonata, i.e., a dragonfly or damselfly. |
| Ommatidium | An individual unit of the compound eye. Plural: Ommatidia. |
| Ovipositing | The process of laying eggs. |
| Ovipositor | Blade-like structure used to lay the eggs into plant tissue; located beneath Segments 8-10 in females of Zygoptera and Aeshnidae (other females have a Vulvar Scale). |
| Term | Definition |
|---|---|
| Polymorphic | Occurring in different forms, especially of colour (polychromatism). |
| Posterior | Positioned at the rear of the body. Antonym: Anterior. |
| Prolarva | The short first Stadium immediately after hatching. The Larva is still enclosed in a membrane and lacks functional legs and mouthparts. |
| Pronotum | A shield-like plate covering the top of the Prothorax. The shape of the rear edge hind lobe is Diagnostic in many damselflies, especially females. |
| Prothorax | The first Segment of the Thorax, bearing the forelegs, situated between the head and Synthorax. |
| Pruinescence, Pruinose, Pruinosity | A pale bluish or greyish waxy bloom that develops on the Abdomen and Thorax on some species as they mature, particularly noticeable in some male Chaser and Skimmer dragonflies, and some Emerald damselflies. |
| Pseudopterostigma | A coloured area of the wing found in female demoiselles, similar in appearance to a true Pterostigma, but is probably decorative. |
| Pterostigma | A small thickened patch towards the end of the leading edge of each wing. Generally a different colour to the rest of the wing, mostly a dark rectangle. Thought to help counterbalance the wing. |
| Term | Definition |
|---|---|
| Reticulation | See Venation. |
| Term | Definition |
|---|---|
| SSSI | Site of Special Scientific Interest. A conservation area that’s of particular interest to science due to the rare species of fauna or flora it contains. |
| Secondary Genitalia | Male organs beneath Segments 2 and 3 of the Abdomen, used for storage and transfer of sperm. The male transfers sperm from his primary genitalia (at the Posterior of the Abdomen) to his secondary genitalia, enabling him to inseminate the female whilst clasping her using the Anal Appendages. |
| Segment, Urite | Used to describe the 10 divisions of the Abdomen, labeled S1, S2, S10, etc. |
| Semivoltine | Completing a generation every two years. |
| Seta | Hair-like structures on the body surface, generally with some sensory function. Plural: Setae. |
| Spiracles | Small openings on the sides of each thoracic and abdominal Segment, through which air enters an insect’s respiratory system. |
| Stadium | In larval development, the period between one moult and the next. Depending on the species, a Larva may pass through 8-18 stadia; the Prolarva is the first stadium. Some texts use the term Instar interchangeably. See also Ecdysis. |
| Subnode | Oblique vein that branches down from the Node. |
| Suture | Fine flexible grooves between Segments of the body which allow movement, e.g., on the Thorax sides and in the face. |
| Synthorax | The Posterior Segment of the Thorax, comprising of the fused Mesothorax and Metathorax, which bears the two pairs of wings and the mid legs and hind legs. |
| Term | Definition |
|---|---|
| Tail-Light | Conspicuous patch of colour near end of Abdomen, particularly in damselflies. |
| Tandem | Describes a male coupled with a female, either prior to or immediately following copulation. The male uses Anal Appendages to clasp the female by the head (dragonflies) or Pronotum (damselflies). In some species the tandem coupling lasts during egg laying. |
| Tarsus | Terminal leg segments, three of them make up the ‘foot’. Plural: Tarsi. |
| Teneral | A newly emerged adult prior to first flight, where the Cuticle has not yet fully hardened and usually lacks adult colouring, the wings are pristine and shiny. Teneral adults are sexually immature. |
| Thorax | The middle portion of an insect’s body, bearing the legs and wings. Comprised of the Prothorax and Synthorax. |
| Tibia | Long thin leg segment below the ‘knee’ (‘shin’). Plural: Tibiae. |
| Term | Definition |
|---|---|
| Univoltine | Completing a generation in one year. |
| Urite | See Segment. |
| Term | Definition |
|---|---|
| Venation | The network of veins in the wings. |
| Ventral | Underside of a body. Antonym: Dorsal. |
| Vulvar Scale | A flap below S8 in females of species that do not oviposit into plant tissue. Can be prominent in some species and be useful in identification. |
| Vulvar Spine | Spine found in some female damselflies on the underside of S8, useful in identification. |
| Term | Definition |
|---|---|
| Zygopteran | Relating to the suborder of Damselflies (Zygoptera). Zygoptera means ‘Equal wings’, referring to Damselflies similarly sized pairs of wings. |