Glossary of Terms

I've compiled a glossary of terms that crop up in references, gleaned from a variety of sources, that I hope may be of use.


Abdomen Posterior part of body, consisting of ten Segments and ending with appendages. The 'tail' of a dragonfly.
Anal Appendages 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.
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.
Basal At or towards the base; that part of a wing, leg, etc., that is closest to the Thorax. Antonym: Apical
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.
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 Aeshna grandis – Brown Hawker.
Cuticle The tough, waterproof, protective outer layer made of chitin, which covers the body of insects and many other arthropod invertebrates.
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 of colour.
Dorsal Upper surface of a body. Antonym: Ventral.
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 into plant tissue. See also Exophytic.
Epiphytic The method of Ovipositing onto the surface of plants.
Estivation Laying dormant during summer. See also Hibernation.
Exophytic The method of Ovipositing on the surface of the water or substrate. See also Endophytic.
Exuvia The skin shed by Larvae. Plural: Exuviae.
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.
Hawking Flying back and forth over an area searching for prey. Characteristic of some lager dragonflies.
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).
Instar See Stadium.
Imago The adult stage of an insect's life.
Jizz The general appearance and first impressions that one obtains of a species in the field.
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 The stage of Odonate life spent underwater prior to Emergence, lasting up to several years dependant on climate and species. Plural:Larvae
Lateral Relating to the side of an object. Antonym: Medial.
Mask See Labium
Medial Along the middle or centre line. Antonym: Lateral.
Node A noticeable 'notch' of the Costa, roughly midway between base and Pterostigma. Thought to make the wing more flexible, significant during hovering.
Nymph Outmoded term used for Larva.
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.
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).
Polymorphic Existing 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 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 dragonflies.
Pseudopterostigma A coloured area of the wing found in female demoiselles, looks similar to a true Pterostigma, but is probably purely 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.
Reticulation See Venation
SSSI Site of Special Scientific Interest.
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 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 A discreet stage of larval development; each time a Larva sheds its skin it enters a new stadium. Depending on the species, a Larva may pass through 8-18 stadia; the Prolarva is the first stadium. Formerly known as an Instar. See 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.
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. 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 hardened, usually with a lack of full colouring on the body making it a pale straw colour, 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.
Univoltine Completing a generation in one year.
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.
Zygopteran Relating to the suborder of Damselflies (Zygoptera). Zygoptera means 'Equal wings', referring to Damselflies similarly sized pairs of wings.