Insect Glossary

INSECT GLOSSARY

Snakefly male (Agulla sp.), photo by Werner Eigelsreiter

From The Insect Families of British Columbia

R. A. Cannings and G. G. E. Scudder

Abdomen. The hindmost of the three main body divisions of an insect.

Acuminate. Tapering to a long point.

Adventive. Not native and not fully established; locally or temporarily naturalized

Aedeagus. Intermittent organ in most insects, formed from a subdivision of the primary phallic lobes.

Alate. Winged; having wings.

Amphibious. Able to live both on land and in water.

Anal. Pertaining to last abdominal segment which bears the anus.

Anal lobe. Posterior lobe of wing.

Annulate. Formed in ring-like segments or with ring-like markings.

Antenna (pl., Antennae). Pair of segmented appendages located on the head and usually sensory in function - the 'feelers'.

Antennal. Relating to the antenna.

Apophysial pits. An exoskeletal pit and evidence of an internal apophysis.

Apophysis. An elongate projection from the exoskeleton, either internally or externally.

Appendage. Any limb or other organ, such as an antenna, which is attached to the body by a joint

Aptera. Primitive wingless insect group.

Apterous. Without wings.

Apterygote. Any member of the Apterygota -primitively wingless insects (i.e. insects which have never developed wings during their evolutionary history) in modern classifications this includes the Thysanura, but not Collembola, Diplura, and Protura which are no longer considered insects, but are termed Hexapods instead.

Aquatic. Living in water.

Arculus. In adult Odonata, an arch-shaped vein connecting radius and median near base of wing, forming an elongate triangle between them.

Articulate. Consisting of segments united by joints.

Atrial chamber. Cuticular chamber immediately internal to spiracle.

Auriculate. Ear-like.

Axillary sclerites. Sclerites at base of wing.

Bifurcate. Two-pronged, or divided into two branches or parts.

Buccula (pl. Bucculae). Flanges on venter of head, on each side of the first segment of the labium in Heteroptera.

Callus. A rounded swelling: applied especially to swollen regions at the front or back of the thorax.

Capitate. With an apical knob-like enlargement.

Carina. A ridge or keel.

Castes. Groups of individuals that become irreversibly behaviorally distinct at some point prior to reproductive maturity. One of three or more distinct forms which make up the population among social insects. The usual three castes are queen, drone (male), and worker. The termites and some of the ants have one or more soldier castes as well.

Cauda. The pointed end of the abdomen in aphids.

Caudal. Concerning the tail end.

Cells. An area of the wing bounded by a number of veins. A cell is closed if it is completely surrounded by veins and open if it is bounded partly by the wing margin.

Cerci. (singular: Cercus) The paired appendages, often very long, which spring from the tip of the abdomen in many insects.

Ciliate. Bearing minute setae.

Ciliation. Synonym of chaetotaxy, namely the description of the arrangement of setae.

Circulus (pl., Circuli). An adhesive organ on the abdominal venter of Pseudococcidae.

Claval commissure. Junction of hemelytra along clavus in middle of dorsum, posterior to scutellum in Heteroptera.

Clavus. Parallel-sided and sharply pointed anal area of hemelytron.

Claw. Sharp curved pincer-like process terminating the segmented thoracic limbs of various arthropods.

Clypeus. Lowest part of the insect face, just above the labrum.

Collophore. Ventral tube in Collembola.

Compound eye. Eye made up of an aggregation of separate visual elements, known as ommatidia, each of which corresponds to a single facet of the cornea.

Concave. Hollowed or rounded inward.

Contiguous. Touching - usually applied to eyes (see also Holoptic).

Convex. Bulging or rounded outward.

Coriaceous. Leather-like in texture.

Corium. The main part of the forewing of a heteropteran bug.

Cornea. Cuticle covering the compound eye or ocellus.

Cornicle. One of the pair of small tubular outgrowths on the hind end of the aphid abdomen.

Cosmopolitan. Occurring throughout most of the world.

Costa (C). The first longitudinal vein of the wing, usually running along the anterior margin.

Costal. Relating to the costa.

Coxa. The basal segment of the insect leg.

Crepitate. In some Acrididae, making a crackling noise by snapping the hindwings in flight.

Crepuscular. Active in the twilight.

Crochets. Hooked spines at tip of the prolegs of lepidopterous larvae.

Crossvein. A short vein joining any two neighboring longitudinal veins.

Cryptic. Colouring and or pattern adapted for the purpose of protection from predators or prey by concealment.

Cubital. Belonging to the cubitus.

Cubitus (Cu). The sixth longitudinal vein of the wing, immediately behind the media (M).

Cuneus. A more or less triangular region of the forewing of certain heteropteran bugs, separated from the corium by a groove or suture.

Cursorial. Adapted for running.

Cuticle. Outer covering of insect, secreted by the epidermis.

Cuticular. Pertaining to the cuticle.

Dens (pl., Dentes). In Collembola, the long proximal segment of the distal arms of the forks of the mannbrium, bearing the mucro apically.

Denticle. A conical pointed projection, as a small tooth.

Denticulate. Bearing very small tooth-like projections.

Dicondylar. With two condyles or basal attachments to the head capsule.

Diurnal. Active in daytime.

Digitate. Finger-like.

Digitules. In Coccoidea, a pair of normally capitate setae at inner base of tarsal claws.

Dimorphic. Occurring in two distinct forms.

Dorsal. On or concerning the back or top of an animal.

Ecomorphosis. A phenomenon where certain life stages are characterized by reduced activity and distinct morphological change.

Ectognathous. With mouthparts freely exposed beyond head capsule, and visible externally.

Ectoparasite. A parasite that lives on the outside of its host.

Elytra. The tough, horny forewing of a beetle or an earwig.

Emarginate. With a distinct notch or indentation in the margin.

Endemic. Restricted to a well defined geographical region.

Endophallus. Internal sac or tube of aedeagus.

Entognathous. With mouthparts sunk into head capsule, and not usually visible externally.

Evaporatorium. Part of cuticle of thorax, modified for rapid evaporation of scent gland fluid.

Eversible. Capable of being turned outward or inside-out.

Exoskeleton. Collectively the external sclerites of the integument.

Explanate. Spread out and flattened.

Exuvia. The cast-off outer skin of an insect or other arthropod.

Eyes. Organs of sight.

Face. Front of head between compound eyes.

Facet. The surface of an ommatidium - one of the units making up the compound eye.

Facetted. With facets.

Facultative. Exhibiting an indicated lifestyle under some environmental conditions, but not under others.

Femur (pl., Femora). The 3rd (counting out from the body) and often the largest segment of the insect leg.

Filament. A thread-like structure.

Filiform. Thread-like or hair-like, applied especially to antennae.

Flabellate. With projecting flaps on one side, applied especially to antennae.

Flagellomere. One part of a multi-divided flagellum.

Flagellum. The distal (furthest away from the body) part of the antenna, the 3rd primary segment of the antenna.

Foliaceous. Resembling a leaf.

Fontanelle. Pore on frontal region of head of termite.

Forceps. Pinchers at end of body.

Foreleg. A front leg.

Forewing. Either of the anterior wings, borne on the mesothorax.

Fossorial. Adapted for digging.

Frons. Upper part of the insect face, between and below the antennae and usually carrying the median ocellus or simple eye.

Furca (pl., Furcula). Forked spring or leaping appendage on fourth abdominal segment of Collembola.

Fusiform. Tapering toward each end.

Genitalia. The copulatory organs of insects and other animals. The shape and arrangement of the genitalia are often used to distinguish closely related and otherwise very similar species.

Gill. Breathing organ possessed by many aquatic creatures, including numerous young insects. Insect gills are usually very fine outgrowths from the body and they contain numerous air-tubes, or tracheae. Oxygen passes into the tubes from the water by diffusion.

Glabrous. Without setae.

Glossa. The inner most pair of lobes at the tip of the labium or lower lip: usually very small, but long in honey bees and bumble bees, in which the two glossae are used to suck up nectar.

Gonangulum. Sclerite attached to base of first valve of ovipositor in female insects, and linking to tergum 1X, and parts of ovipositor derived from segment 1X.

Haltere. One of the club-shaped 'balancers' found on each side of the metathorax among the true flies (Diptera). They are the much-modified hindwings.

Haustellum. Distal portion of proboscis in adult Diptera.

Head. The anterior body region of insects which bears the mouthparts, eyes, and antennae.

Hemelytra. One of the basally thickened fore wings of Hemiptera.

Hemimetabolous. Having an incomplete metamorphosis, with no pupal stage in the life history.

Herbivorous. Feeding on plants.

Hexapod. Animal with six legs.

Hindleg. A back leg.

Hindwing. Either of the posterior wings, borne on the metathorax.

Holocyclic. Life cycle of aphid species with sexual reproduction on winter host and no migration to a summer host plant.

Holometabolous. Having a complete metamorphosis, with larval and pupal stages in the life history.

Hypognathous. Having a vertical head and face with the mouth-parts at the bottom.

Hypopharyngeal. Relating to the hypopharyax.

Hypopharyax. Median lobe in mouth parts, immediately behind the mouth.

Imaginal. Pertaining to the adult or imago.

Imago. The adult insect.

Incrassate. Thickened.

Insectavorous. Depending on insects as food.

Instar. The stage in an insect's life history between any two moults. A newly-hatched insect which has not yet moulted is said to be a first-instar nymph or larva. The adult (imago) is the final instar.

Integument. The outer layer of the insect.

Intercalaries. Additional, interpolated or inserted between, as in wing veins.

Intercubital. In Plecoptera, crossveins between Cu1 and Cu2 in the forewing.

Johnston's organ. A sense organ located in the second antennal segment of many insects and particularly well developed in male mosquitoes and certain other Diptera.

Jugal. Pertaining to the jugum, the basal area of the wing, usually set-off by a jugal fold.

Labial. Concerning the labium.

Labium. The mouthparts, or appendage on the sixth head segment, forming a 'lower lip'.

Labrum. The 'upper lip' of the insect mouth-parts: not a true appendage, but a movable sclerite on the front of the head.

Lacinia. The inner branch of the maxilla, the outer one being the galea

Larva. Name given to a young insect which is markedly different from the adult: caterpillars and fly maggots are good examples.

Lateral. Concerning the sides.

Ligula. Name given to the lobe at the tip of the labium: usually divided into glossae and paraglossae.

Ligulate. Strap-shaped.

Linear. Elongated with nearly parallel sides.

Lorum (pl., Lora). Plate lateral to the clypeus in Hemiptera.

Macropterous. Having long or large wings.

Macroseta. A seta conspicuously larger than adjacent setae.

Mandible. The jaw of an insect. It may be sharply toothed and used for biting, as in grasshoppers and wasps, or it may be drawn out to form a slender needle as in mosquitoes. Mandibles are completely absent in most flies and lepidopterans.

Mandibulate. Having mandibles suited for biting and chewing.

Manubrium. In Collembola, the large median base of the fucula.

Maxilla (pl., Maxillae). One of the two components of the insect mouth-parts lying just behind the jaws. They assist with the detection and manipulation of food and are often drawn out into tubular structures for sucking up liquids.

Media (M). The fifth longitudinal vein of the wing.

Meron. Posterior part of proximal rim of coxa.

Mesonotum. The dorsal sclerite of the 2nd thoracic segment - the mesothorax: usually the largest thoracic sclerite.

Meso-precoxal bridge. Precoxal part of the pleuron, anterior to the trochantin in the mesothorax.

Mesothorax. The 2nd segment of the thorax.

Mesotrochanter. Trochanter of middle leg.

Metamorphosis. Name given to the changes that take place during an insect's life as it turns from a young animal to an adult. These changes may be gradual and not too large, as in the grasshopper, and metamorphosis is then said to be partial or incomplete. On the other hand, the changes may be much greater and they may take place in one big step - as in the butterflies and moths, which change from caterpillars to adults during the pupal stage. Metamorphosis of this kind is said to be complete.

Metanotum. The dorsal sclerite of the metathorax. It is often very small and its sub-divisions are usually obscured.

Metathorax. The 3rd and last segment of the thorax.

Micropterous. Small or vestigal wings, being more reduced than brachypterous.

Molar, mola. Grinding surface of mandible.

Moniliform. Antennae composed of bead-like segments, each well separated from the next.

Monocondylar. With one condyle or basal attachment to the head capsule.

Monoecious. Having male and female sex organs in the same individual.

Moult. To moult is to shed the outer covering of the body - the exoskeleton.

Mouthparts. Structures or appendages near the mouth, adapted for use in gathering or eating food.

Mucro. The abrupt sharp terminal segment of the furcula in Collembola.

Multiocular. Having many openings.

Neck. The part of an animal that connects the head with the body.

Nocturnal. Active at night.

Nodus. The kink or notch on the costal margin of the dragonfly wing. The name is also used for the strong, short cross-vein just behind the notch.

Notal. Pertaining to the notum.

Notum. Dorsal sclerite of thoracic segment.

Nymph. Name given to the young stages of those insects which undergo a partial metamorphosis. The nymph is usually quite similar to the adult except that its wings are not fully developed. It normally feeds on the same kind of food as the adult.

Obligatory. Not optional.

Obtuse. Not pointed or acute.

Ocellus (pl., Ocelli). One of the simple eyes of insects, usually occurring in a group of three on the top of the head, although one or more may be absent from many insects.

Ochraceous. Pale brownish-yellow in colour.

Omnivorous. Feeding on both animal and vegetable substances.

Omphalium. Metasternal opening of metathoracic scent gland in adult Gerridae.

Ootheca. An egg case formed by the secretions of accessory genital glands or oviducts, such as the purse-like structure carried around by cockroaches or the spongy mass in which mantids lay their eggs.

Operculate. Having a body process or part that suggests a lid.

Orifice. An opening, as a vent, mouth, or hole through which something may pass.

Ostiole. A small bodily aperture, orifice, or pore.

Oviparous. Producing eggs which are hatched outside the body of the female.

Ovipositor. The tubular or valved egg-laying apparatus of a female insect: concealed in many insects, but extremely large among the bush-crickets and some parasitic hymenopterans.

Ovisac. A waxen sac into which eggs are laid in Coccoid Hemiptera, and which sometimes encloses all or part of the female.

Pala. Tarsus of foreleg of Corixidae, modified into a seta-fringed scoop.

Palp. A segmented leg-like structure arising on the maxilla or labium. Palps have a sensory function and play a major role in tasting food.

Papilla. A small projecting body part similar to a nipple in form.

Parabollically. With two or more non-parallel sides.

Paraglossa. The outer most pair of lobes at the outer edges of the tip of the labium: with the central glossae, the paraglossae make up the ligula.

Paramere. Copulatory hooks formed from outer subdivision of primary phallic lobes.

Paraproct. One of the 2 lobes bordering the sides of the anus.

Paratergite. Lateral subdivision of tergum.

Parthenogenetic. Reproducing by parthenogenesis, that is with egg developing without fertilization.

Penis (pl. Penes). Intromittent organ formed from primary phallic lobes without subdivision.

Pentagonal. Having five sides and five angles.

Penultimate. The next to the last member of a series.

Phragma (pl. Phragmata). Internal plate providing attachment for longitudinal muscles in meso and metathorax.

Phylogenetic. Having natural evolutionary relationships.

Pilose. Densely clothed with setae.

Pleura. Pleural of pleuron. The lateral region of a thoracic segment.

Pleurodema. External sulcus of pleural apophysis.

Plicate. Having the surface thrown up into or marked with parallel ridges, being folded or pleated.

Polymorphic. A species having several forms independent of the variations of sex.

Polyphagous. Feeding on a variety of plants and or animals.

Porrect. Extending horizontally forward: applied especially to antennae.

Postantennal angle. In Anoplura, angular part of head behind the antenna.

Prehensile. Adapted for seizing or grasping especially by wrapping around.

Primary phallic lobes. Pair of ectodermal outgrowths that give rise to all or part of intromittent organ in insects.

Proboscis. Name given to various kinds of sucking mouths in which some of the mouth-parts are drawn out to form tubes.

Prognathous. Having a more or less horizontal head, with the mouth-parts at the front.

Proleg. Hollow, paired, non-segmented outgrowth of abdominal segments of holometabolous larvae, usually used in locomotion.

Pronotum. The dorsal sclerite of the 1st thoracic segment.

Prosternal. Pertains to the sternum of the prothoracic segment.

Prothorax. The 1st or anterior thoracic segment.

Pseudocellus. Thin walled oval structure on the head of Collembola.

Pterostigma. A small coloured area near the wing-tip of dragonflies, bees, and various other clear-winged insects: also called the stigma.

Pulvilli (singular Pulvillus). Bladder-like appendages arising ventrally between claws.

Punctate. Covered with tiny pits or depressions, like the elytra of many beetles and the thoraxes of many hymenopterans.

Pupa (pl., Pupae). The 3rd stage in the life history of butterflies and other insects undergoing a complete metamorphosis during which the larval body is rebuilt into that of the adult insect a non-feeding and usually inactive stage.

Pygidium. A caudal structure or the terminal body region of various invertebrates.

Pyriform. Having the form of a pear.

Quadrangle. Four-sided discoidal cell in Odonata wing, positioned between the anterior median and posterior cubitus, and immediately distal to posterior segment of arculus.

Quadrate. In the form of a square.

Radial. Arranged or having parts arranged like rays.

Radius (R). Third longitudinal vein of wing.

Raptorial. Adapted for seizing and grasping prey, like the -front legs of a mantis.

Rectal. Relating to, affecting, or being near the rectum.

Rectum. In insects, the posterior expanded part of the hindgut, typically pear shaped.

Repose. To lay at rest.

Reticulate. Covered with a network pattern.

Rhinaria (singular rhinarium). Sense organs on the antennae of in aphids.

Rostral. Of or relating to a rostrum.

Rostrum. A beak or snout, applied especially to the piercing mouth-parts of bugs and the elongated snouts of weevils.

Rotary. Capable of rotating, or turning entirely around.

Scale. A flat unicellular outgrowth of the integument.

Scavenger. An organism that feeds habitually on refuse or carrion.

Sclerite. A sclerotized plate in the exoskeleton or integument.

Sclerotized. Hardened especially by the formation of sclerotin: an insoluble tanned protein permeating and stiffening the chitin of the cuticle of arthropods.

Scutellum. The 3rd of the major divisions of the dorsal surface of a thoracic segment: usually obvious only in the mesothorax and very large in some bugs.

Segment. One of the rings or divisions of the body, or one of the sections of a jointed limb.

Sensoria. Circular sensory organs on antennae or legs.

Serrate. Toothed like a saw.

Sessile. Attached to one place and unable to move, like many female scale insects.

Seta. (pl. Setae). A sclerotized hair-like structure of the insect cuticle, arising from a single cell, and surrounded at base by thin cuticular ring.

Setose. With setae.

Spatulate. Shaped like a spatula or spoon.

Spermatophore. A packet of sperm.

Spine. A multicellular, thorn-like process or outgrowth of the integument not separated from it by a joint.

Spiniform. In the form of a spine.

Spinule. A minute spine.

Spinulose. Having minute spines.

Spiracle. One of the breathing pores - openings of the tracheal system - through which diffusion of gases takes place. They usually occur on the third thoracic segment and all the abdominal.

Stemmata. The simple eyes in holometabolous larvae. Also called lateral ocellus.

Sternum. Ventral sclerite of a segment.

Stigma (pl. Stigmata). Small, thickened, and coloured area near the wing-tip of dragonflies, bees, and various other clear-winged insects: also called the pterostigma.

Stria. Groove running across or along the body: applied especially to the grooves on beetle elytra.

Striate. Marked with grooves running across or along the body.

Stridulate. To make a sound by rubbing two ridged or roughened surfaces together.

Stridulation. The production of sounds by rubbing two parts of the body together: best known in grasshoppers and other orthopterans.

Stylets. Needle-like form: applied to the various components of piercing mouthparts and also to a part of the sting of a bee or other hymenopteran.

Styli. Small finger-like process.

Subcosta (Sc.). The second, usually unbranched, longitudinal wing vein, posterior to the costa.

Subgenital. Below the genitalia.

Subimaginal. Pertaining to the subimago, the first imaginal instar of mayflies.

Subimago. First adult instar of the first imaginal instar of mayflies.

Sulcate. Scored with usually longitudinal furrows.

Sulcus (pl. Sulci). Shallow furrows.

Suture. A groove on the body surface which usually divides one plate or sclerite from the next: also the junction between the elytra of a beetle.

Symbiotic. The state of living together of two dissimilar organisms in a mutually beneficial relationship.

Tarsi (pl. Tarsus). An insect's foot: primitively a single segment beyond the tibia, but usually consisting of several subdivisions or segments in most living insects.

Tarsomere. Subdivision of the primary tarsal segment.

Tegmen. The leathery forewing of a grasshopper or similar insect, such as a cockroach

Tegminization. To become tegmina-like.

Tegmina (pl. Tegman). The leathery forewing of Orthopteroid insects..

Telofilum. The median tail filament, being a prolongation of tergum X1.

Tenaculum. In Collembola, a minute appendage with two divergent prongs, situated medially on the ventral surface of the third abdominal segment, serving to hold the furcula in place.

Tentorium. Endoskeleton of the head.

Terminal. Of or relating to an end, extremity, or boundary.

Terrestrial. Living on or in, or growing from land.

Test. In most Coccids a scale covering, consisting of exuvial, secreted waxy material and excrement.

Thorax. The middle of the three major divisions of the insect body. The legs and wings (if present) are always attached to the thorax.

Tibia. The forth leg segment between the femur and the tarsus.

Tibiotarsus. In Collembola, the fourth segment of the leg.

Trachea (pl., Tracheae). One of the minute tubes which permeate the insect body and carry gases to and from the various organs etc. They open to the air at the spiracles.

Triangle. A triangular region near the base of the dragonfly wing, often divided into smaller cells.

Trichobothrium. A fine sensory seta.

Triommatidium. A reduced compound eye in apterous aphids with 3 separate lenses.

Triradiate. Having three rays or radiating branches.

Trochanter. The second segment of the leg, between coxa and femur: often very small and easily overlooked.

Trochantin. Free sclerotized remnant located at the base of the leg, providing a second point of pleural articulation with the coxa.

Truncate. Ending abruptly: squared off.

Tubercle. A small knob-like or rounded protuberance.

Tuberculate. Having tubercles: small knob-like or rounded protuberances.

Tuberculiform. Having the form of a tubercle.

Turbinate. Having a shaped like a top or an inverted cone.

Tylus. The distal part of the clypeus in Hemiptera.

Tympanum. The auditory membrane or ear-drum of various insects.

Vannal. Same as anal area or lobe of wing.

Vein. In insects, the rib-like tube that strengthen the wings.

Venation. The arrangement of veins in the wings of insects.

Ventral. Being or located near or on the lower surface.

Vertex. The top of the head, between the eyes.

Vestigial. Poorly developed, degenerate or atrophied, more fully functional in an earlier stage of development of the individual or species.

Wingpad. The undeveloped wing of nymphs and naiads, which appear as two flat structures on each side.