Entomology List/Ametabolous and Apterygota

This page contains information on Ametabolous and Apterygote Orders. For information on how to use this list, please see the first section on the Entomology List page. For more general information about the event, see Entomology.

Ametabolous and Apterygote Orders

Protura (telsontails, proturans)

Head: Entognathous (retracted within the head), sucking mouthparts, consist of thin mandibles & maxillae, use mouthparts to scrape off food particles, which they draw into mouth & mix with saliva; No antennae; No eyes; Head Conical, Pseudoculi (eye shaped organs, unknown usage) present (may be remnants of vestigial antennae); conical head;
Thorax: Wingless; FL used for sensory function, 5 segmented, each leg tipped with a single claw;
Abdomen: 12 Abdominal Segments (newly hatched have 9, each time they molt, one is added), Small ventral styli located on abdominal segments 1-3, Cerci & Abdominal filaments entirely absent; Some lack a tracheal system (All gas exchange occurs through the integument); walk using four rear legs; post-anal telson at end, no cerci at abdomen end; during mating the genitalia are everted from an abdominal chamber;
Sexual Dimorphism: Genitalia are internal & the genital opening lies between the eleventh segment & the telson of the adult;
Misc Anatomy: .6-1.5mm; Unpigmented, most white or ivory; Postanal Telson @ end of cylindrical body; elongated and cylindrical body; Function of the antennae is fulfilled by the first pair of the three pairs of five-segmented legs, which are held up, pointing forward, and bearing numerous tarsal sensilla and sensory hairs.
Human Impact: None are pests, help break down/recycle organic nutrients;
Habitat: Always moist, usu in the humus & leaf mold of temperate deciduous forests, some live 10” underground; Uncommon;
Diet: Organic matter released by decay & mycorrhizal fungi, dead Acari, & mushroom powder in culture; Herbivores
Explanation of Name: "Proto” – first (original) “ura” – tail;, refers to the lack of advanced or specialized structures at the back of the abdomen
Misc: Most primitive hexapods, smallest arthropod class; Discovered by Antonio Sylvestri in 1907 near Syracuse, New York;

Entognathous, sucking mouthparts all enclosed within head capsule, consist of thin mandibles & maxillae, use mouthparts to scrape off food particles, which they draw into mouth & mix with saliva; No antennae; No eyes; Head Conical, Pseudoculi (eye shaped organs for smell) present (may be remnants of vestigal antennae); Wingless; FL used as sensory function, 5 segmented, each leg tipped with a single claw; 12 Abdominal Segments (newly hatched have 9, each time they molt, one is added), Small ventral styli located on abdominal segments 1-3, Cerci & Abdominal filaments entirely absent; Genitalia are internal & the genital opening lies between the eleventh segment & the telson of the adult; Some lack a tracheal system (All gas exchange occurs through the integument); .6-1.5mm; Unpigmented, most white or ivory; Postanal Telson at end of cylindrical body; None pests, help break down/recycle organic nutrients; Always moist, usu in the humus & leaf mold of temperate deciduous forests, some live 10” underground; Uncommon; Herbivores; Organic matter released by decay & mycorrhizal fungi, dead Acari, & mushroom powder in culture; Most primitive hexapods, smallest arthropod class; “proto” – first (original) “ura” – tail; Discovered by Antonio Sylvestri in 1907 near Syracuse, New York;

Collembola (springtails, snow fleas)

Head: Piercing-sucking, entognathic mouthparts; Antennae short with 4-6 segments: Compound eyes absent or reduced to a cluster of not more than 8 ommatidia;
Thorax: Wingless; Most have short legs, 1 segmented tarsi;
Abdomen: Unique, tube-like structure, the collophore is located ventrally on the first abdominal segment (possibly helps maintain water balance by absorbing fluid), Forked jumping organ (furcular) on 4th abdominal segment; The furcula is retracted against the ventral wall of the abdomen & held there, in cocked position, by a special catch (the tenaculum) on the third abdominal segment. Effective adaptation for avoiding predation;
Sexual Dimorphism: Genital opening on 5th abdominal segment;
Life Cycle: Young similar in appearance to adults but paler, some parthenogenetic, most sexual reproduction;
Human Impact: Decompose/ recycle organic materials, some are plant pests;
Habitat: Common in grassy/wooded areas decaying organic matter, spores, some inhabit the intertidal zone; Common, worldwide;
Diet: Scavengers, use ants or termites as a host (commenalism); Feed on decaying vegetation & soil fungi;
Explanation of Name: “coll” – glue, “embol”- wedge (referring to furcula that was once thought to function as an adhesive organ);
Misc: Most abundant soil-dwelling arthropods; Appear to have evolved in cold climate;

Piercing-sucking, entognathic mouthparts; Antennae short with 4-6 segments: Compound eyes absent or reduced to a cluster of not more than 8 ommatidia; Wingless; Most have short legs; Unique, tube-like structure, the collophore is located ventrally on the first abdominal segment (possibly helps maintain water balance by absorbing fluid), Forked jumping organ (furcular) on 4th abdominal segment; The furcula is retracted against the ventral wall of the abdomen & held there, in cocked position, by a special catch (the tenaculum) on the third abdominal segment. Effective adaptation for avoiding predation; Genital opening on 5th abdominal segment; Young similar in appearance to adults but paler, some parthenogenetic, most sexual; 1-5mm; Variety of colors; Variable body shapes; Body frequently clothed with scales; Decompose/ recycle organic materials, some are plant pests; Common in grassy/wooded areas decaying organic matter, spores, some inhabit the intertidal zone; Common, worldwide; Scavengers, use ants or termites as a host (commenalism); Feed on decaying vegetation & soil fungi; Most abundant soil-dwelling arthropods; “coll” – glue, “embol”- wedge (referring to furcula); Appear to have evolved in cold climate;

Diplura (diplurans)

Head: Chewing/biting mouthparts; Antennae longer than head w/ 10 bead-like segments projecting forward; Lack Eyes; mouth is concealed in a pouch by the lateral margins of the head capsule; mandibles have some apical teeth
Thorax: Wingless; 3 pairs of walking legs, regenerate lost legs through molts, Tarsi 1 segmented; Move thru soil by pushing with wormlike movements or using tunnels/crevices;
Abdomen: Abdomen with 10 visible segments, Paired cerci at rear (either pincer like in appearance OR long & slender {means they’re herbivores}), small, eversible vesicles on the ventral side of first 7 abdominal segments that help regulate the body's water balance, possibly by absorbing moisture from the environment; may have different types of setae or a mix of setae and scales
Sexual Dimorphism: Sexes are separate & fertilization is external, Males produce sperm packets (spermatophores) & glue them to the substrate on the end of little stalks, Females use their genital opening to gather spermatophores & then lay their eggs on little stalks inside a crevice or small cavity in the ground; in males glandular setae/disculi might be there in first abdominal sternite
Life Cycle: Molt many times throughout life; mating around 30 times per life and life=1 year;
Misc Anatomy: 2-50mm, most 7-10mm; Whitish in color due to lack of pigmentation due to subterranean lifestyle, cerci usually darker; Elongated body; Some cerci adapted to break off if mishandled (Autotomy); external genitalia on eighth abdominal segment
Human Impact: Not pests, Important decomposers;
Habitat: Grassy places in New Zealand, Australia, Live in moist soil, leaf litter, or humus; Common (but seldom seen because of size & reclusive habits); favor tropical and temperate regions; all land except antarctica
Diet: Predators OR herbivores if have long cerci; Eat Wide variety of other soil-dwellers, including collembola, mites, symphyla, insect larvae, & even other diplurans OR vegetable debris & fungal mycelia (animal prey preferred);
Explanation of Name: “Diplo” – two, “Ura” – tails;
Misc: Among the most primitive hexapods, early diplurans had compound eyes and mouthparts which indicate closer relationships with true insects; also known as two-pronged bristletails, diplurans;

Mode of Life/Habitat: Common in moist soil, leaf litter or humus. They have biting mouthparts and feed on a variety of live prey and dead organic matter. Like other non-insect hexapods, diplurans practice external fertilisation. Males lay up to 200 spermatophores a week, which are held off the ground by short stalks and probably only remain viable for about two days. The female collects the spermatophore with her genital opening, and later lays eggs in a cavity in the ground. The hatchlings (or nymphs) do not undergo metamorphosis, but resemble the adults, apart from their smaller size, lesser number of setae and their lack of reproductive organs. Diplurans are common in moist soil, leaf litter or humus, but are rarely seen because of their size and subterranean lifestyles. They have biting mouthparts and feed on a variety of live prey and dead organic matter. Those species with long cerci are herbivorous. Diplurans are found on nearly all land masses, except Antarctica and several oceanic islands. Their role as soil-dwelling organisms may play a key role in indicating soil quality, and as a measure of anthropogenic impact (e.g. soil nutrient depletion as a result of farming)

Chewing/biting mouthparts; Antennae longer than head w/ 10 bead-like segments; Lack Eyes; Wingless; 3 pairs of walking legs, regenerate lost legs through molts, Tarsi 1 segmented; Move thru soil by pushing with wormlike movements or using tunnels/crevices; Abd 10 visible segments, Paired cerci at rear (either pincer like in appearance OR long & slender {means they’re herbivores}), small, eversible vesicles on the ventral side of first 7 abdominal segments that help regulate the body's water balance, possibly by absorbing moisture from the environment; Sexes are separate & fertilization is external, Males produce sperm packets (spermatophores) & glue them to the substrate on the end of little stalks, Females use their genital opening to gather spermatophores & then lay their eggs on little stalks inside a crevice or small cavity in the ground; Molt many times throughout life; 2-5mm; Whitish in color, cerci usually darker; Elongated body; Some cerci adapted to break off if mishandled (autotomy); Not pests, Important decomposers; Found- grassy places in New Zealand, Australia, Live in moist soil, leaf litter, or humus; Common (but seldom seen because of size & reclusive habits); Predators OR herbivores if have long cerci; Wide variety of other soil-dwellers, including collembola, mites, symphyla, insect larvae, & even other diplurans OR vegetable debris & fungal mycelia (animal prey preferred); Among most primitive hexapods; “Diplo” – two, “Ura” – tails;

Thysanura (bristletails, silverfish)

Head: Short mandibles, unspecialized mouthparts; Antennae long, thread-like, & multi-segmented; Compound eyes small or absent;
Thorax: Wingless
Abdomen: Abdomen with ten complete segments, 11th segment elongated to form a median cadual filament; 3 cerci (nearly as long as median cadual filament), styliform appendages located on abdominal segments 7-9;
Sexual Dimorphism: Elaborate Courtship ritual (male spins a silken thread between the substrate & a vertical object then depositsa sperm packet beneath the thread & gets a female to walk through. When her cerci contact the silk thread, she picks up the spermatophore with her genital opening. Sperm enters her reproductive system & she eats the empty sperm packet;
Life Cycle: Relatively long lived, 3 years;
Misc Anatomy: Less than 1 cm long; Sliver scales covering bodies; Flattened, elongated, oval-shaped;
Human Impact: Can cause extensive damage to household goods (wallpaper paste, book bindings, starch, cardboard, paper products);
Habitat: Domestic & sylvan (wooded) habitats worldwide; Common; Hide under stones/leaves during the day & emerge after dark for food;
Diet: Scavengers/browsers; Eat many things- algae, lichens, or starchy vegetable matter…;
Explanation of Name: "thysano-" fringed, ‘ura’- tail; refers to the long, fringed filaments on the abdomen

Short mandibles, unspecialized mouthparts; Antennae long, thread-like, & multi-segmented; Compound eyes small or absent; Wingless; Abdomen with ten complete segments, 11th segment elongated to form a median cadual filament; 3 cerci (nearly as long as median cadual filament), styliform appendages located on abdominal segments 7-9; Elaborate Courtship ritual (male spins a silken thread between the substrate & a vertical object then depositsa sperm packet beneath the thread & gets a female to walk through. When her cerci contact the silk thread, she picks up the spermatophore with her genital opening. Sperm enters her reproductive system & she eats the empty sperm packet; Relatively long lived, 3 years; Less than 1 cm long; Sliver scales covering bodies; Flattened, elongated, oval-shaped; Can cause extensive damage to household goods (wallpaper paste, book bindings, starch, cardboard, paper products); Domestic & sylvan (wooded) habitats worldwide; Common; Scavengers/browsers; Eat many things- algae, lichens, or starchy vegetable matter…; Hide under stones/leaves during the day & emerge after dark for food; "thysano-" fringed, ‘ura’- tail;