Glossary

Terms

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There are currently 116 names in this directory
aedeagus
A tube-like organ which enters the female's body during copulation (like a penis)

aeropyles
Microscopic pores in the chorion that allow respiratory exchange of oxygen and carbon dioxide with relatively little loss of water.

ametabolous
adjective - refers to insects where adults and nymphs are wingless, and there is no visible change in form between the stages, other than in size. Ametabolous development occurs in the wingless insects apterogytes and in other groups that undergo simple metamorphosis where the adults are wingless (1). ametabola refers to this group of insects (sometimes called apterogytes), includes: Zygentoma - Silverfish Microcoryphia - Bristletails

apodeme
A ridge-like ingrowth of the exoskeleton that supports the internal organs and provides the attachment points for the muscles.

apolysis
Physical separation of the epidermis from the old endocuticle during molting.

apophyses
Finger-like invaginations of exoskeleton; an elongate apodeme (an internal projection of the exoskeleton)

blood sinus
A body cavity where the blood flows in the insect's open circulatory system.

bursa copulatrix
The part of the female genitalia which receives the aedeagus and sperm during copulation

campodeiform
Larval body type often called crawlers. Elongated, flattened body with prominent antennae and/or cerci; thoracic legs adapted for running.Example: lady beetle larva

cement layer
Layer of epicuticle that protects the wax layer from heat or abrasion.

cerci
Paired sensory appendages on the rear-most segments of some "primitive" insects. In some cases, they may also serve as weapons or copulation aids.

chorion
The protective "shell" of protein covering the insect's egg that is secreted before oviposition by accessory glands in the female's reproductive system.

chrysalis
Pupal stage of holometabolous insects in which developing appendages (antennae, wings, legs, etc.) are held tightly against the body by a shell-like casing. Often found enclosed within a silken cocoon. Ex. Butterflies and moths

cibarium
The portion of the preoral cavity between the hypopharynx and the labrum

cleavage energids
In an embryo, the daughter nuclei cleavage products and their surrounding cytoplasm.

clypeus
Facial sclerite located just below the epistomal suture

coarctate
Pupal body type. Body is encased within the hard exoskeleton of the next-to-last larval instar. Example: Flies

collophore
A fleshy, peg-like structure found in Collembola on the ventral side of the first abdominal segment. It appears to maintain homeostasis by regulating absorption of water from the environment.

corona
The dorsal, anterior region of the head capsule; equivalent to the forehead.

coronal suture
Suture along dorsal midline of head; runs backwards from the vertex along the top of the head

coxa
The basal segment of the leg, by means of which it is articulated to the body

cuticulin layer
The innermost layer of epicuticle that is composed of lipoproteins and chains of fatty acids embedded in a protein-polyphenol complex.

ecdysis
Shedding the old exo- and epicuticle

eclosion
The emergence of an adult insect from its pupal case, or the hatching of an insect larva from an egg. From the French eclosion, from eclore, to open.

ectoderm
In embryonic development, the germ layer giving rise to the epidermis, exocrine glands, brain and nervous system, sense organs, foregut and hindgut, respiratory system, and external genitalia.

elateriform
Larval body type often called wireworms. Long, smooth, and cylindrical body with hard exoskeleton and very short thoracic legs. Example: Click beetle, flour beetle

endocrine glands
Secretory structures adapted for producing hormones and releasing them into the circulatory system

endocrine system
A group of hormone-secreting structures that help maintain homeostasis, coordinate behavior, and regulate growth, development, and other physiological activities

endoderm
In embryonic development, the germ layer giving rise to the midgut.

epicuticle
The epicuticle is the outermost part of the cuticle. Its function is to reduce water loss and block the invasion of foreign matter.

epiproct
The epiproct is the last dorsal sclerite at the tip of the abdomen. It covers and protects the anus from above.

epistomal suture
The epistomal suture runs along the ventral side of the frons. It separates the frons from the clypeus

eruciform
Larval body type often called caterpillars. Cylindrical body with short thoracic legs and 2-10 pairs of fleshy abdominal prolegs. Example: Moths and butterflies

exarate
Pupal body type. All developing appendages are free and visible externally. Example: Beetles and lacewings

femur
The long leg segment between the trochanter and tibia

flagellomere
The three basic segments of the antenna are the scape (base), the pedicel (stem), and the flagellum, which is comprised of units known as flagellomeres.

flagellum
Long, apical segment of the antenna, commonly subdivided into several subsegments (flagellomeres)

frons
The frons is the front of the face. It lies between the frontal sutures and above the epistomal suture.

frontal sutures
Frontal sutures separate the frons from the gena.

furca
A special "strut" of exoskeleton that reinforces the ventral corners of each thoracic segment and provides a rigid site for attachment of leg muscles and ventral longitudinal muscles.

furcula
The furcula ("little fork" in Latin) or wishbone is a forked bone found in birds and some other animals, and is formed by the fusion of the two clavicles. In birds, its primary function is in the strengthening of the thoracic skeleton to withstand the rigors of flight.

gastrulation
A phase early in the development of the embryo during which the morphology of the embryo is reorganized to form the three embryonic germ layers: ectoderm, mesoderm, and endoderm. Each layer gives rise to specific tissues and organs in the developing embryo.

gena
The lateral "cheek" region of the head that lies behind the frontal sutures on each side of the head

germ band
Blastoderm cells on one side of the egg begin to enlarge and multiply. This region, known as the germ band (or ventral plate), is where the embryo's body will develop.

hemimetabolous
Hemimetabolous insects exhibit gradual changes in body form during morphogenesis. Immatures are called nymphs or, if aquatic, naiads.

holometabolous
insects which pass through a complete metamorphosis in which the larva is very different from the adult and does not become more like the adult, but transforms dramatically by means of a pupal stage

imaginal discs
Latent adult structures in an immature insect which are clusters of undifferentiated (embryonic) tissue that form during embryogenesis but remain dormant throughout the larval instars.

imago
An insect is known as an imago (adult) when it becomes sexually mature. At this point, molting stops and energy for growth is channeled into production of eggs or sperm.

instar
The growth stage between two successive molts.

labium
The labium is the most posterior of the insect's mouthparts. Its sclerites are fused along the midline to form a back lip. A pair of labial palps are sensory in function.

labrum
The labrum is the most anterior of the insect's mouthparts. It is a flat sclerite that serves as a front lip.

malpighian tubules
A multitude of long, spaghetti-like structures that extend throughout most of the abdominal cavity where they serve as excretory organs, removing nitrogenous wastes (principally ammonium ions, NH4+) from the hemolymph. The toxic NH4+ is quickly converted to urea and then to uric acid by a series of chemical reactions within the Malpighian tubules.

mandibles
A pair of highly sclerotized, unsegmented "jaws" located between the labrum and maxillae

maxillae
Pair of mouthparts located just behind the mandibles. They help manipulate the food and include a pair of maxillary palps that are sensory in function.

mesoderm
In embryonic development, the germ layer giving rise to the heart, blood, circulatory system, muscles, endocrine glands, fat body, and gonads (ovaries and testes).

micropyle
A special opening near the anterior end of the chorion that serves as a gateway for entry of sperm during fertilization.

molting
The periodic formation of new exoskeleton, often accompanied by structural changes in the body wall and other organs, followed by ecdysis (the shedding of old exoskeleton)

naiad
The immature instar of an aquatic hemimetabolous insect

neurohemal organs
Specialized organs, similar to glands, that store their secretory product in a special chamber until stimulated to release it by a signal from the nervous system (or another hormone).

neurosecretory cells
Specialized nerve cells (neurons) that respond to stimulation by producing and secreting specific chemical messengers. Functionally, they serve as a link between the nervous system and the endocrine system.

notum
Dorsal region of a thoracic segment

obtect
Pupal body type called a chrysalis. Developing appendages (antennae, wings, legs, etc.) are held tightly against the body by a shell-like casing. Often found enclosed within a silken cocoon. Example: Butterflies and moths

occiput
A sclerite that circles the foramen magnum and forms the posterior surfaces of the head capsule

ocelli
Three "simple" eyes, one adjacent to each compound eye and one in the central groove

ootheca
Production of an öotheca is a special adaptation found only in the cockroaches and praying mantids. The female's reproductive system secretes a special capsule around her eggs. This structure, known as an öotheca, may be dropped on the ground, glued to a substrate, or retained within the female's body.

ovipary
The type of reproduction occurring in most insects in which life begins as an independent egg.

ovipositor
The female's ovipositor is used to lay eggs. It consists of two large pairs of valvulae for digging into the soil and a smaller pair of valvulae for manipulating the egg during oviposition.

paramere
Genital appendages of the male that are divided into the external and internal mera (parts).(plural paramera)

paraproct
Paired sclerites on each side of the epiproct. They cover and protect the sides of the anus.

pedicel
The second antennal segment, between the scape and the flagellum

periplasm
The egg cell's cytoplasm is usually distributed in a thin band just inside the vitelline membrane (where it is commonly called periplasm).

peritrophic membrane
A semipermeable membrane lining the midgut that protects the delicate digestive cells without inhibiting absorption of nutrient molecules. It consists of chitin fibrils embedded in a protein-carbohydrate matrix.

phallobase
In male genitalia, the support for the aedeagus (the male copulatory organ)

pile
Tiny hair-like projections or surface sculpturing of the cuticle are known as microtrichae or pile. These acellular structures consist of a solid core of exocuticle covered by a thin layer of epicuticle.

pleural wing process
In thoracic segments that bear wings, the pleural apodeme runs dorsally into the pleural wing process, a finger-like sclerite that serves as a pivot or fulcrum for the base of the wing.

pleuron
The lateral plate of each insect segment -- it is usually divided by a pleural suture into at least two sclerites:; an anterior episternum and a posterior epimeron.

Pretarsus
The terminal segment of the tarsus and any other structures attached to it.

procuticle
A multi-layered region of the exoskeleton that lies immediately above the epidermis. It contains microfibers of chitin surrounded by a matrix of protein that varies in composition from insect to insect and even from place to place within the body of a single insect.

prothoracic glands
A pair of endocrine glands found in the prothorax (behind the head) that manufacture ecdysteroids ("molting hormones")

raptorial
Legs adapted for catching and holding prey

rectal pads
Six organs embedded in the walls of the rectum that efficiently facilitate the recovery of more than 90% of the water from a fecal pellet before it passes out of the body through the anus.

saltatorial
Legs adapted for jumping

scale
A flattened seta (hair); often pigmented. Characteristically found covering the body and wings of Lepidoptera.

scape
The basal segment of an insect antenna that articulates with the head capsule

scarabaeiform
Larval body type often called white grubs. Robust and "C"-shaped body with no abdominal prolegs and short thoracic legs. Example: June beetle and dung beetle

sclerites
Rigid "plates" of exoskeleton surrounded by membrane or sutures are known as sclerites.

sclerotization
Hardening of the cuticle; sclerites harden and darken as quinone cross-linkages form within the exocuticle. This process (also called tanning) gives the exoskeleton its final texture and appearance.

serosa
Cells in the blastoderm become part of a membrane (the serosa) that forms the yolk sac. Cells from the serosa grow around the germ band, enclosing the embryo in an amniotic membrane.

setae
Larger hairs, bristles, and scales (called setae or macrotrichae) that project from the integument. (sing. seta)

spiracles
Spiracles are valve-like openings in the exoskeleton that regulate the flow of air into and out of the tracheal system. Spiracles are located laterally along the thorax and abdomen of most insects -- usually one pair per body segment.

spurs
Multicellular projections of the exoskeleton are called spines (or spurs, if movable). They are lined with epidermis and contain both procuticle and epicuticle.

sternite
Simple sclerite that covers the ventral surface of each abdominal surface; a subdivision of a sternum.

sternum
Ventral thoracic sclerites are called sterna (or sternites).

stigma
Rectangular stigma (pigmented patch) near tip of each wing of dragonflies and damselflies

stylet
One of the elongate parts of piercing-sucking mouthparts; a needle-like structure.

subgenital plate
The subgenital plate closes over and protects the male genitalia. The male's aedeagus is usually hidden away under the subgenital plate.

subimago
Winged "subadult" that undergoes one molt and becomes the adult; unique to mayflies (Ephemeroptera)

suture
An external shallow groove at the junction between two sclerites.

tagma
In biology a tagma (Greek: τάγμα, plural tagmata - τάγματα) is a specialized grouping of multiple segments or metameres into a coherently functional morphological unit. Familiar examples are the head, the thorax, and the abdomen of insects.

tarsomere
A subdivision of the tarsus (the leg segment distal to the tibia)

tarsus
Distal, segmented part of the insect leg attached to the tibia; usually subdivided into 1-5 tarsomeres

tenaculum
A minute structure on the sternum of the third abdominal segment which serves as a clasp for the furcula of collembolans

tentorium
Inside the head, the tentorium serves as an internal "truss" that reinforces the head capsule, cradles the brain, and provides a rigid origin for muscles of the mandibles and other mouthparts.

tergum
Simple sclerite that covers the dorsal surface of each abdominal segment

thorax
Middle portion of the body between the head and abdomen, consisting of three segments (prothorax, mesothorax, and metathorax), each of which usually bear a pair of articulated legs

tibia
Long leg segment located between the femur and the tarsus

tormogen cell
The socket-forming epidermal cell associated with a seta.

tracheal system
A complex network of tubes that delivers oxygen-containing air to every cell of the insect's body.

trichogen cell
A hair-forming epidermal cell associated with a seta.

trochanter
Small segment of the leg that articulates with the coxa and forms an immovable attachment with the femur

valvifers
Basal sclerites with muscle attachments that support the valves of the ovipositor.

valvulae
Apical sclerites of the ovipositor which guide the egg as it emerges from the female's body.

vermiform
Larval body type often called maggots. Fleshy, worm-like body with no head capsule or walking legs. Example: House fly and flesh fly

vertex
The vertex is the forehead - - where the head narrows to a point.

vitelline membrane
An egg's cell membrane made up of a phospholipid bilayer similar in structure to most other animal membranes. It surrounds the entire contents of the egg cell.

wax layer
The lipid or waxy layer that lies just above the cuticulin layer; it serves as the chief barrier to movement of water into or out of the insect's body.