Dragonflies and Damseflies Glossary: Insects of West Virginia Website

Insects of West Virginia

Dragonflies and Damselflies Glossary

Abdomen. The rearmost part of the insect, coming behind the head and thorax. The addomen is usually enlongated and cylindrical in Odonates. See also segments.

Apex. The portion of a body part that is farthest of the central body or from the base. The apex of an antenna is the tip. The apex of the pronothorax is the part nearest the head. The apex of the abdomen is the posterior (rearmost) portion. The plural of apex is apices. The opposite of apex is base.

Apical. Pertaining to the apex.

Auricles. A pair of ear-like appendages that in some species project from each side of the dragonfly’s body.

Basal. Pertaining to the base; see Base.

Base.The portion of a body part that is closest to the central body and farthest from the apex. For example, the base of an antenna is the part nearest the head. The opposite of base is apex.

Cerci. Paired appendages at the tip of the abdomen (arising on segment 10). The singular of cerci is cercus.

Claspers. Appendages at the rear of an Odonate male, used to clasp the female to form the tandem position and the wheel position.

Congener. Said of a species that is in the same genus as the species at hand.

Costa. Thickened leading edge of a wing.

Crepuscular. Active at twilight.

Dorsal. Pertaining to the dorsum, the "back" of the Odonate.

Diurnal. Active during the day; the opposite of diurnal is nocturnal.

Ecdysis. The shedding of the outer cuticle; molting.

Edges. The side margins of a structure.

Emergence. Refers to the nymph’s leaving the water for the final molt.

Exuviae. The molted skin. Most often the term is used to refer to the skin left behind after the final molt. The term is plural but singular variations (exuvia and exuvium) are seldom used.

Eyespots. A pair of spots in the postocular area of damselflies. Their color, size, and shape are often used in species identification. In some cases a thin bar connects the two eyespots.

Femur. The first elongate leg segment. Moving away from the body, the femur is attached to the tibia which is then attached to the tarsi. The plural of femur is femora.

Frons. The dorsal surface of the anterior part of the head; the "forehead."

Humeri. The front two corners of the thorax. The singular of humeri is humerus.

Hyaline. Colorless and transparent; glass-like.

In tandem. See Tandem

Instar. A period in the life of a larva, either between hatching and the first molt, or between two molts.

Labium. The lower lip.

Labrum. The upper lip, a structure that covers the base of the mandibles.

Longitudinal. Going in the "length" direction on the Odonate as opposed to the "width" direction. For example, a long stripe along the upper surface of the abdomen is longitudinal. The opposite of longitudinal is transverse.

Mandibles. The upper pair of jaws.

Margins. The edges of a structure.

Naiad. The aquatic larva of an Odonate. This term is less favored today than in previous years; most writers now simply use the term larva.

Nodus. A prominent cross-vein near the center of the leading edge of a wing.

Oblique. At an angle; neither horizontal nor vertical; diagonal. Many Odonates (for example, the Spreadwings) perch obliquely. Also, many Odes (for example, the Aeshna darners) have oblique stripes on the sides of the thorax.

Oblisking. Pointing the abdomen upward from a perched position, typically to reduce the heating effect of the sun’s rays.

Ocelli. Simple eyes. The singular of ocelli is ocellus.

Occiput. The part of the head behind the vertex.

Odonates. Members of the order Odonata. Dragonflies, including Damselflies.

Oviposit. To lay eggs.

Ovipositor. The part of the female’s body used to lay eggs; sometimes ovipositors have a blade that cuts slits in the plant where eggs are laid.

Palpus. A short, segmented structure; one pair is located on the maxillae and one pair on the labium. The plural of palpus is palpi.

Postocular area. The posterior dorsal surface of the head. Located between the compound eyes and to the rear of the ocelli.

Prolarva. A hatchling; prolarvae typically molt quickly into the next stage.

Prothorax. The anterior part of the thorax.

Pruinose. With a waxy covering on the cuticle. Often the pruinescence increases with age, obscuring markings and giving the insect a whitish to bluish appearance.

Pterostigma. A cell on the leading edges of the wings, typically in a color contrasting with the rest of the wing.

Pubescent. Bearing soft, short hairs.

Segment, abdominal. One of ten clearly demarcated sections of rearmost part of the Odonate. There is a standard numbering system, shown in the illustration, with segment 10 (for example) being the rearmost section of the abdomen.

Setae. Bristles, stiffened hairs. The singular of setae is seta.

Shoulders. The front two corners of the thorax. Also called the humeri.

Sinuate. Said of a line or an edge that is wavy.

Stigma. A cell on the leading edges of the wings, typically in a color contrasting with the rest of the wing. In some cases traits of the stigma can be used in species identification, or to help separate the male from the female of a species.

Striae. Impressed lines. The singular of striae is stria.

Striate. With striae present.

Striations. Same as striae.

Tandem. A posture in which two Odonates are joined, the male in the lead and the female behind, the male’s claspers holding the female by the "neck." Many species oviposit in tandem. The tandem position may also be adopted prior to assuming the wheel position for mating.

Tarsus. The apcial section of the leg, made up of two to five segments; the "foot." At its basal end the tarsus is attached to the tibia. The plural of tarsus is tarsi.

Teneral. Said of a nymph or adult that has just molted and has pale coloration and a soft body.

Thoracic stripes. Contrasting stripes on the sides or the dorsum of the thorax, often a key trait in identification.

Tibia. The shin; the middle section of the leg located between the femur and the tarsus. At its basal end the tibia is attached to the femur; at its apical end the tibia is attached to the tarsus. The plural of tibia is tibiae.

Transverse. Going in the "width" direction on the Odonate as opposed to the "length" direction. For example, short lines across each abdominal segment are said to be transverse. The opposite of transverse is longitudinal.

Vertex. A flattened area of the head, posterior to the frons.

Wheel position. The posture assumed by a pair of odonates prior to mating.

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This Odonates Glossary is a part of the Insects of West Virginia website. Text and photographs © 2009.

All the photos on this page are of West Virginia Odonates.