CLASS: INSECTA Sub—class: APTERYGOTA* Primitively wingless insects with no true metamorphosis. Abdom inal appendages present other than gonopophyses and cerci.
Small insects with long, many jointed antennae : abdomen of ten segments and bearing prominent cerci. Includes the bristle-tails.
Very minute insects without antennae: abdomen of 12 segments, cerci wanting.
Very small insects with four-jointed antennae: abdomen of six segments, sometimes fused together, the first with a sucker-like ventral tube and the fourth usually with a forked springing organ. Includes the spring-tails.
Sub-class : PTERYGOTA Winged insects (sometimes wingless through loss of flight
gans) : metamorphosis more or less evident. No abdominal
pendages other than genitalia and cerci.
Wings developed outside the body: metamorphosis incomplete or scarcely evident in the wingless species.
Fore-wings leathery, hind-wings membranous with posterior lobe folded up fan-wise. Prothorax large : mouth-parts for biting, with four-lobed ligula : cerci pres ent. Includes cockroaches, grasshoppers, locusts, crickets, stick insects and leaf-insects: some forms are wingless.
Fore-wings small leathery flaps, hind-wings large, membranous, complexly folded up. Mouth parts for biting, with two-lobed ligula : tarsi three-jointed : the body terminated by forceps. Includes the earwigs (q.v.), many of which are wingless : also Hemimerus and Arixenia which are rare wingless forms, without forceps, living on mammals.
Soft-bodied insects with long thread-like antennae ; wings membranous, folded flat over the back in repose ; the hind pair usually largest and with a posterior lobe folded up fan-wise. Mouth-parts for biting, tarsi three jointed : cerci often elongate. Nymphs aquatic, often with tufted gills. Includes the stone-flies.
Soft-bodied in sects with atrophied mouth-parts and minute antennae. Wings membranous, net-veined, hind pair much the smaller : tarsi one to five-jointed : cerci long, many-jointed and often accompanied by a median tail-filament. Nymphs aquatic with tracheal gills. Includes the may-flies (q.v.).
Large insects with very elongate bodies, large eyes and minute antennae. Two pairs of equal, membranous, net-veined, glassy wings. Mouth parts for biting: tarsi three-jointed: cerci small, one-jointed. Nymphs aquatic, labium modified into a hinged prehensile or gan. Includes the dragon-flies (q.v.).
Social insects living in large nests: soft-bodied and generally pale coloured : either with two pairs of elongate similar wings which are soon shed, or without wings. Mouth-parts for biting : tarsi almost always four-jointed: cerci very short. Wingless forms with rudimentary eyes or none at all and usually of two types; viz., soldiers with large heads and jaws or a pointed rostrum, and workers with normal heads and jaws. Includes the termites (q.v.) or white ants. (See also SOCIAL IN
