Glossary of terms used in Odonata references

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.

AbdomenPosterior part of body, consisting of ten Segments and ending with appendages. The ‘tail’ of a dragonfly.
Anal AppendagesVariable 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 LoopDistinct group of cells in the hind wing base of Anisopteran dragonflies; its shape can be Diagnostic.
Andromorph, HomeomorphA female with colouring similar to that of a male. Antonym: Heteromorph
AnisopteranRelating to the suborder of true Dragonflies (Anisoptera). Anisoptera means ‘unequal wings’, referring to the larger hind wing of Dragonflies.
Antehumeral StripesStripes on the dorsal surface of the Thorax. Usually pale in colour.
AnteriorTowards the front, e.g. the leading edge of the wing. Antonym: Posterior.
Apex, ApicalAt or towards the tip. e.g. that part of a wing that is furthest from the Thorax. Antonym: Basal.
BasalAt or towards the base; that part of a wing, leg, etc., that is closest to the Thorax. Antonym: Apical
CaudalRelating to the tail, e.g. caudal lamellae are situated at the rear of a damselfly’s body.
Caudal LamellaeThree fan-like structures situated at the end of the Abdomen in damselfly Larvae, used as respiratory and swimming organs.
ClypeusThe lower part of the face, below the Frons.
CostaThick vein along the entire leading edge of the wings.
CoxaThe segment of leg that connects it to the Thorax (‘hip’). Plural: Coxae.
ConspecificBelonging to the same species.
CrepuscularSpecies that are active at dusk (often also active at dawn and during daytime in dense forest), such as the Brown Hawker – Aeshna grandis.
CuticleThe tough, waterproof, protective outer layer made of chitin, which covers the body of insects and many other arthropod invertebrates.
DiagnosticA distinguishing feature that confirms an identification.
DiapausePeriod 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.
DimorphicHaving two distinct forms, especially when this relates to colour.
DorsalUpper surface of a body. Antonym: Ventral.
EcdysisThe periodic moulting of the 'skin' of a Larva, enabling growth. Marks the end of one Stadia and the beginning of the next.
EmergenceThe process of a Larva leaving the water and shedding its skin, before drying out and hardening, and eventually flying off as an immature adult.
EndophyticThe method of Ovipositing into plant tissue. See also Exophytic.
EstivationLaying dormant during summer. See also Hibernation.
ExophyticThe method of Ovipositing by dropping or laying eggs into water. See also Endophytic.
ExuviaThe skin shed by Larvae. Plural: Exuviae.
FemurThe long leg segment above the ‘knee’ (‘thigh’). Plural: Femora
FormDiscrete alternative appearance of individuals within populations, especially in female colouration. See also Polymorphic.
FronsThe dorsal part of face. The ‘forehead’ of a dragonfly.
HawkingFlying back and forth over an area searching for prey. Characteristic of some larger dragonflies.
HemimetabolousA 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.
HeteromorphTypical colouration of a female, differing from the male, usually duller. Antonym: Andromorph
HibernationLaying dormant during winter. See also Estivation.
Humeral StripesDark stripes on the humeral suture of the Thorax. Useful in identifying damselflies.
HyalineClear or transparent (especially with respect to wings).
InstarThe discreet stage of larval development following each moult. Described as first, second, third etc. Some texts use the term Stadium interchangeably. See Ecdysis.
ImagoThe adult stage of an insect’s life, distinct from any Larval or Nymph stage.
JizzThe general appearance and first impressions that one obtains of a species in the field.
Labium or MaskLower 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.
LabrumLower portion of face, upper lip-like structure shielding the mandibles from the front.
LarvaAlternative (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.
LateralRelating to the side of an object. Antonym: Medial.
MaskSee Labium
MedialAlong the middle or centre line. Antonym: Lateral.
NaiadThe 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.
NodeA noticeable ‘notch’ of the Costa, roughly midway between base and Pterostigma. Thought to make the wing more flexible, significant during hovering.
NymphCommon term used for Naiad, especially in dragonflies and damselflies.
Occipital TriangleTriangular area on the dorsal surface of the back of head (Occiput) lying between the eyes in Anisoptera (except Gomphidae).
OcciputThe area of the head behind the eyes.
OcellusA 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.
OdonateA member of the insect order Odonata, i.e., a dragonfly or damselfly.
OmmatidiumAn individual unit of the compound eye. Plural: Ommatidia.
OvipositingThe process of laying eggs.
OvipositorBlade-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).
PolymorphicOccurring in different forms, especially of colour (polychromatism).
PosteriorPositioned at the rear of the body. Antonym: Anterior.
ProlarvaThe short first Stadium immediately after hatching. The Larva is still enclosed in a membrane and lacks functional legs and mouthparts.
PronotumA shield-like plate covering the top of the Prothorax. The shape of the rear edge hind lobe is Diagnostic in many damselflies, especially females.
ProthoraxThe first Segment of the Thorax, bearing the forelegs, situated between the head and Synthorax.
Pruinescence, Pruinose, PruinosityA 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.
PseudopterostigmaA coloured area of the wing found in female demoiselles, similar in appearance to a true Pterostigma, but is probably decorative.
PterostigmaA 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.
ReticulationSee Venation.
SSSISite 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 GenitaliaMale 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.
SegmentUsed to describe the 10 divisions of the Abdomen, labeled S1, S2, S10, etc.
SemivoltineCompleting a generation every two years.
SetaHair-like structures on the body surface, generally with some sensory function. Plural: Setae.
SpiraclesSmall openings on the sides of each thoracic and abdominal Segment, through which air enters an insect’s respiratory system.
StadiumIn 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 Ecdysis.
SubnodeOblique vein that branches down from the Node.
SutureFine flexible grooves between Segments of the body which allow movement, e.g., on the Thorax sides and in the face.
SynthoraxThe 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-LightConspicuous patch of colour near end of Abdomen, particularly in damselflies.
TandemDescribes a male coupled with a female either prior to or immediately following copulation. In some species the tandem coupling lasts during egg laying.
TarsusTerminal leg segments, three of them make up the ‘foot’. Plural: Tarsi.
TeneralA 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.
ThoraxThe middle portion of an insect’s body, bearing the legs and wings. Comprised of the Prothorax and Synthorax.
TibiaLong thin leg segment below the ‘knee’ (‘shin’). Plural: Tibiae.
UnivoltineCompleting a generation in one year.
VenationThe network of veins in the wings.
VentralUnderside of a body. Antonym: Dorsal.
Vulvar ScaleA 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 SpineSpine found in some female damselflies on the underside of S8, useful in identification.
ZygopteranRelating to the suborder of Damselflies (Zygoptera). Zygoptera means ‘Equal wings’, referring to Damselflies similarly sized pairs of wings.