See also:

• HEXAPODA (Gr. 4, six, and gobs, foot)

HEXAPODA (Gr. 4, six, and gobs, See also:

• FOOT

foot)  , a See also:

• TERM

term used in systematic See also:

• ZOOLOGY (from Gr. Nov, a living thing, and ?byos, theory)

zoology for that class of the See also:

• ARTHROPODA

ARTHROPODA, popularly known as See also:

• INSECTS

insects . See also:

• LINNAEUS

Linnaeus in his Systema nalurae (1735) grouped under the class Insecta all segmented animals with See also:

• FIRM

firm exoskeleton and jointed limbs—that is to say, the insects, centipedes, millipedes, crustaceans, See also:

• SPIDERS

spiders, scorpions and their See also:

• ALLIES, THOMAS WILLIAM (1813-1903)

allies . This assemblage is now generally regarded as a See also:

• GREAT

great See also:

• DIVISION (from Lat. dividere, to break up into parts, separate)

division (phylum or sub-phylum) of the See also:

• ANIMAL
• ANIMAL (Lat. animalis, from anima, breath, soul)

animal See also:

• KINGDOM

kingdom and known by K . T . E. von See also:

• SIEBOLD, CARL THEODOR ERNST VON (1804–1885)
• SIEBOLD, PHILIPP FRANZ VON (1796-1866)

Siebold's (1848) name of Arthropoda . For the class of the true insects included in this phylum, Linnaeus's old term Insecta, first used in a restricted sense by M . J . See also:

• BRISSON, EUGENE HENRI (1835– )
• BRISSON, MATHURIN JACQUES (1723-1806)

Brisson (1756), is still adopted by many zoologists, while others prefer the name See also:

• HEXAPODA (Gr. 4, six, and gobs, foot)

Hexapoda, first used systematically in its See also:

• MODERN

modern sense by P . A . See also:

• LATREILLE
• LATREILLE, PIERRE ANDRE (1762–1833)

Latreille in 1825 (Families naturelles du regne animal), since it has the See also:

• ADVANTAGE

advantage of expressing, in a single word, an important characteristic of the See also:

• GROUP

group . The terms "Hexapoda " and " hexapod " had already been used by F . See also:

• WILLUGHBY, FRANCIS (1635—1672)

Willughby, J .

See also:

• RAY (Lat. raia)
• RAY (or WRAY, as he wrote his name till 1670), JOHN (1628-1705)

Ray and others in the See also:

• LATE

late See also:

• LATH (0. Eng. laett, Mid. Eng. lappe, a form possibly due to the Welsh llath; the word appears in many Teutonic languages, cf. Dutch lat, Ger. Latte, and has passed into Romanic, cf. Ital. latta, Fr. latte)

lath See also:

• CENTURY (from Lat. centuria, a division of a hundred men)

century to include the active larvae of beetles, as well as bugs, lice, fleas and other insects with undeveloped wings . Ckaracters . A true See also:

• INSECT

insect, or member of the class Hexapoda, may be known by the grouping of its See also:

• BODY

body-segments in three distinct regions—a See also:

• HEAD (in 0. Eng. heafad; the word is common to Teutonic languages; cf. Dutch hoofd, Ger. Haupt, generally taken to be in origin connected with Lat. caput, Gr. KerbOvi7)
• HEAD, SIR EDMUND WALKER, BART
• HEAD, SIR FRANCIS BOND, BART

head, a See also:

• THORAX (Gr. BWpaE, breastplate, also the part of the body covered by it)

thorax and an See also:

• ABDOMEN (a Latin word, either from abdere, to hide, or from a form adipomen, from adeps, fat)

abdomen—each of which consists of a definite number of segments . In the terminology proposed by E . R . Lankester the arrangement is " nomomer- istic " and " nomotagmic." The head of an insect carries usually four pairs of conspicuous appendages — feelers, mandibles and two pairs of maxillae, so that the presence of four See also:

• PRIMITIVE

primitive somites is immediately evident . The See also:

• COMPOUND
• COMPOUND (from Lat. componere, to combine or put together)

compound eyes of insects resemble so closely the similar See also:

• ORGANS

organs in Crustaceans that there can hardly be reasonable doubt of their homology, and the primitively appendicular nature of the eyes in the latter class suggests that in the Hexapoda also they represent the appendages of an anterior (protocerebral) segment . Behind the antennal (or deutocerebral) segment an " See also:

• INTERCALARY (from Lat. intercalare, to proclaim, calare, the insertion of a day in the calendar)

intercalary " or tritocerebral segment has been demonstrated by W . M . See also:

• WHEELER, JOSEPH (1836-1906)
• WHEELER, WILLIAM ALMON (1819-1887)

Wheeler (1893) and others in various insect embryos, while in the lowest insect See also:

• ORDER
• ORDER (through Fr. ordre, for earlier ordene, from Lat. ordo, ordinis, rank, service, arrangement; the ultimate source is generally taken to be the root seen in Lat. oriri, rise, arise, begin; cf. " origin ")
• ORDER, HOLY

order—the See also:

• APTERA (Greek for " wingless ")

Aptera—a pair of See also:

• MINUTE
• MINUTE (Lat. minutes, small; minuere, to make less)

minute jaws—the maxillulae—in See also:

• CLOSE
• CLOSE (from Lat. clausum, shut)
• CLOSE, MAXWELL HENRY (1822-1903)

close association with the See also:

• TONGUE (O. Eng. lunge)

tongue are See also:

• PRESENT

present, as has been shown by H . J . See also:

• HANSEN, PETER ANDREAS (1795-1874)

Hansen (1893) and J .

W . Folsom (1900) . Distinct vestiges of the maxillulae exist also in the earwigs and booklice, according to G . Enderlein and C . BOrner (1904), and they are very evident in larval may-flies . The number of See also:

• LIMB

limb-bearing somites in the insectan head is thus seen to be seven . All of these are to be regarded as primitively See also:

• POST

post-oral, but in the course of development the mouth moves back to the mandibular segment, so that the first three somitesocular, antennal and intercalary—See also:

• LIE, JONAS LAURITZ EDEMIL (1833—1908)
• LIE, MARIUS SOPHUS (1842–1899)

lie in front of it . In Lankester's terminology, therefore, the head of an insect is" triprosthomerous." The maxillae of the hinder pair become more or less fused together to See also:

• FORM (Lat. forma)

form a " See also:

• LOWER

lower See also:

• LIP (a word common in various forms, to Teutonic languages, cf Ger. Lippe, Dan. laebe; Lat. labium is cognate)

lip " or labium, and the segment of these appendages is, in some insects, only imperfectly See also:

• UNITED

united with the head-See also:

• CAPSULE (from the Lat. capsula, a small box)

capsule . The thorax is composed of three segments; each bears a pair of jointed legs, and in the vast See also:

• MAJORITY (Fr. majorite; Med. Lat. majoritas; Lat. major, greater)

majority of insects the two See also:

• HIND

hind-most See also:

• BEAR
• BEAR, BLACK
• BEAR, BROWN
• BEAR, GRIZZLY
• BEAR, ISABELLINE
• BEAR, WHITE

bear each a pair of wings . From these three pairs of thoracic legs comes the name—Hexapoda—which distinguishes the class . And the wings, though not always present, are highly characteristic of the Hexapoda, since no other group of the Arthropoda has acquired the See also:

• POWER [WILLIAM GRATTAN] TYRONE (1797-1841)

power of See also:

• FLIGHT

flight . In the more generalized insects the abdomen evidently consists of ten segments, the hindmost of which often carries a pair of tail-feelers, (cerci or cercopods) and a terminal anal segment .

In some cases, however, it can be shown that the cerci really belong to an See also:

• ELEVENTH

eleventh abdominal segment which usually becomes fused with the tenth . With very few exceptions the abdomen is without loco-motor limbs . Paired processes on the eighth and ninth abdominal segments may be specialized as See also:

• EXTERNAL

external organs of See also:

• REPRODUCTION

reproduction, but these are probably not appendages . The See also:

• FEMALE

female genital opening usually lies in front of the eighth abdominal segment, the male duct opens on the ninth . In all See also:

• MAIN (from the Aryan root which appears in " may " and " might," and Lat. magnus, great)
• MAIN (Lat. Moenus)

main points of their See also:

• INTERNAL

internal structure the Hexapoda agree with other Arthropoda . Specially characteristic of the class, however, is the presence of a complex See also:

• SYSTEM

system of See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

air-tubes (tracheae) for respiration, usually opening to the exterior by a See also:

• SERIES (a Latin word from serere, to join)

series of paired spiracles on certain of the body segments . The See also:

• POSSESSION
• POSSESSION (Lat. possessio, possidere, to possess)

possession of a variable number of excretory tubes (Malpighian tubes), which are See also:

• DEVELOPED

developed as outgrowths of the hind-gut and pour their See also:

• EXCRETION (Lat. ex, out of, cernere, cretum, to separate)

excretion into the See also:

• INTESTINE (Lat. intestinus, internal, usually in neuter plural intestina. from intus, within)

intestine,is also a distinctive See also:

• CHARACTER (Gr. xapareri7p, from xap&crew, to scratch)

character of the Hexapoda . The wings of insects are, in all cases, developed after hatching, the younger stages being wingless, and often unlike the See also:

• PARENT, SIMON NAPOLEON (1855– )

parent in other respects . In such cases the development of wings and the attainment of the adult form depend upon a more or less profound transformation or See also:

• METAMORPHOSIS

metamorphosis . With this brief See also:

• SUMMARY

summary of the essential characters of the Hexapoda, we may pass to a more detailed See also:

• ACCOUNT
• ACCOUNT (through O. Fr. acont, Late Lat. comptum, cornputare, to calculate)

account of their structure . EXOSKELETON The See also:

• OUTER

outer cellular layer (ectoderm or " hypodermis ") of insects as of other Arthropods, secretes a chitinous cuticle which has to be periodically See also:

• SHED

shed and renewed during the growth of the animal . The regions of this cuticle have a markedly segmental arrangement„ and the definite hardened pieces (sclerites) of the exoskeleton are in close contact with one another along linear sutures, or are united by regions of the cuticle which are less chitinous and more membranous, so as to permit freedom of See also:

• MOVEMENT

movement .

Head.—The head-capsule of an insect (See also:

• FIGS

figs . 1, 2) is composed of a number of sclerites firmly sutured together, so that the primitive segmentation is masked . Above is the See also:

• CROWN

crown (vertex or epicranium), on which or on the " front may be seated three See also:

• SIMPLE

simple eyes(ocelli) . Below this comes the front, and then the See also:

• FACE (from Lat. fades, derived either from facere, to make, or from a root fa-, meaning " appear "; cf. Gr. cbatvstv)

face or clypeus, to which a very distinct upper lip (See also:

• LABRUM (Lat. for " lip ")

labrum) is usually jointed . Behind the lain-See also:

• URN (Lat. urna, either from root of urere, to burn, being made of burnt clay, or connected with urceus, Gr. I5pxa, jar)

urn arises a See also:

• PROCESS

process—the epipharynx—which in some See also:

• BLOOD

blood-sucking insects becomes a formidable piercing-See also:

• ORGAN

organ . On either See also:

• SIDE
• SIDE (mod. Eski Adalia)

side a variable amount of See also:

• CONVEX

convex See also:

• AREA

area is occupied by the compound See also:

• EYE
• EYE (O. Eng. edge, Ger. Auge; derived from an Indo-European root also seen in Lat. oc-ulus, the organ of vision (q.v.)

eye; in many insects of acute sense and accurate flight these eyes are very large and sub-globular, almost See also:

• MEETING (from " to meet," to come together, assemble, 0. Eng. metals ; cf. Du. moeten, Swed. mota, Goth. gamotjan, &c., derivatives of the Teut. word for a meeting, seen in O. Eng. Wit, moot, an assembly of the people; cf. witanagemot)

meeting on the See also:

• MIDDLE

middle See also:

• LINE

line of the head . Below each eye is a cheek area (gene), often divided into an anterior and a posterior See also:

• PART

part, while a distinct See also:

• CHIN

chin-sclerite (See also:

• GULA

gula) is often developed behind the mouth . Feelers.—Most conspicuous among the appendages of the head are the feelers or antennae, which correspond to the anterior feelers (antennules) of See also:

• CRUSTACEA

Crustacea . In their simpler See also:

• CONDITION (Lat. condicio, from condicere, to agree upon, arrange; not connected with conditio, from condere, conditum, to put together)

condition they are See also:

• LONG, GEORGE (1800-1879)
• LONG, JOHN DAVIS (1838– )

long and many-jointed, the segments bearing numerous olfactory and tactile See also:

• NERVE (Lat. nervus, Gr. vevpov, a bowstring)

nerve-endings . Elaboration in the form of the feelers, often a secondary sexual character in Inale insects, may result from a distal broadening of the segments, so that the appendage becomes serrate, or from the development of processes bearing sensory organs, so that the structure is pinnate or See also:

• FEATHER (0. Eng. (ether, Ger. Feder, from an Indo-European root seen also in Gr. lrrepov, and aEreo-Oat, to fly)

feather-like . On the other See also:

• HAND
• HAND (a word common to Teutonic languages; cf. Ger. Hand, Goth. handus)
• HAND, FERDINAND GOTTHELF (1786-185r)

hand, the number of segments may be reduced, certain of them often becoming highly modified in form . Jaws.—The mandibles of the Hexapoda are usually strong jaws with one or more See also:

• TEETH (O.E. Eel); plural of tooth, O.E. top)

teeth at the See also:

• APEX

apex (fig .

1, A,• B, mn)), articulating at their bases with the head-capsule by sub-globular condyles, and provided with abductor and adductor muscles by means of which they can be separated or See also:

• DRAWN

drawn together so as to bite solid See also:

• FOOD
• FOOD (like the verb " to feed," from a Teutonic root, whence O. Eng. foda; cf. " fodder "; connected with Gr. lrareicOae, to feed)

food, or seize See also:

• OBJECTS

objects which have to be carried about . They never bear seg- mented limbs (palps) and only exception- ally (as in the chafers) is the See also:

• SKELETON

skeleton com- posed of more than one sclerite . The mandibles often furnish a See also:

• GOOD, JOHN MASON (1764-1827)

good example of "secondary sexual characters,' being more strongly developed in the male than in the female of the same See also:

• SPECIES

species . In most insects that feed by suction the See also:

• MANDI

mandi- bles are modified . In bugs (Heteroptera) and many flies, for example, they are changed into See also:

• NEEDLE (O. Eng. ncedl; the word appears in various forms in Teutonic languages, Ger. Nadel, Dutch naal, the root being ne-, to sew, cf. Ger. nahen, and probably Lat. nere, to spin, Gr. vi)ats, spinning)

needle-like piercers (fig . 2, II), while in moths and caddis-flies they are reduced to See also:

• MERE
• MERE, ADALBERT (1838-1909)

mere vestiges or altogether After Marlatt Entom . See also:

• BULL
• BULL, GEORGE (1634–1710)
• BULL, JOHN (c. 1562–1628)
• BULL, OLE BORNEMANN (18ro-188o)

Bull. r4, n. s . (D . S . Dept . Agric.). suppressed .. s pprev ar of ntee frons; b, clypeus (the pointed labrum tinned, a Q,n of minute beneath it);II, mandible; 111, first See also:

• LAWS

laws—ths maxillulathe maxilla; (a, See also:

• BASE

base ; b, sheath ; c, piercer), are present in the lowest order of insects, III', inner view of sheath; IV, second between the mandibles maxillae forming rostrum (b, mentum; c, and the first maxillae. ligula) .

They usually consist of an inner and an outer See also:

• LOBE

lobe arising from a basal piece, which bears'also in some genera a small palp (see APTERA) . In their typical See also:

• STATE
• STATE, GREAT OFFICERS OF

state of development, the first maxillae offer a striking contrast to the mandibles, being composed of a two-segmented basal piece (cardo and stipes, fig . 1, C, ca, st) bearing a distinct inner and outer lobe (lacinia and galea, fig . 1, C, la, ga) and externally ajointed limb or palp (fig i, C, pa) . Such maxillae are found in most biting insects . In insects whose mouths are adapted for sucking and piercing, remarkable modifications may occur . In many blood-sucking flies, for example, the galea is absent, while the lacinia becomes a strong See also:

• KNIFE (0. E. cuff, a word appearing in different forms in many Teutonic languages, cf. Du. knijf, Ger. Kneif, a shoe-maker's knife, Swed. knif; the ultimate origin is unknown; Skeat finds the origin in the root of " nip," formerly " knip "; Fr. canif is a

knife-like piercer and the palp is well developed . In bugs and aphids the lacinia is a slender needle-like piercer (fig . 2, III), while the palp is wanting . In butterflies and moths the lacinia is absent while the galea becomes i flexible process, grooved on its inner face, so as to make with its See also:

• FELLOW

fellow a hollow sucking-See also:

• TRUNK (Fr. tronc, Lat. truncus, cut off, maimed)

trunk, and the palp is usually very small . The second pair of maxillae are more or less completely fused together to form what is known as the labium or " lower lip." In generalized biting insects, such as cockroaches and locusts (See also:

• ORTHOPTERA (Gr. Op®os, straight, and rTepov, a wing)

Orthoptera), the parts of a typical maxilla can be easily recognized in the labium . The fused cardines form a broad basal See also:

• PLATE

plate (sub-mentum) and the stipites a smaller plate (mentum)—see fig .

1, C, sm, me-jointed on to the submentum, while the galeae, laciniae and palps remain distinct . In specialized biting insects, such as beetles (See also:

• COLEOPTERA

Coleoptera), the labium tends to become a hard transverse plate bearing the pair of palps, a median structure—known as the ligula—formed of the conjoined laciniae, and a pair of small rounded processes—the reduced galeae—often called the " paraglossae," a term better avoided since it has been applied also to the maxillulae of Aptera, entirely different structures . The long sucking " tongue " of bees is probably a modification of the ligula . In bugs and aphids (See also:

• HEMIPTERA (Gr. 77µi-, half and IrTep6P, a wing)

Hemiptera), the fused second maxillae form a jointed grooved See also:

• BEAK (early forms beke and becke, from Fr. bec, late Lat. beccus, supposed to be a Gaulish word; the Celtic bec and beq, however, are taken from the English)

beak or rostrum (fig . 2, IV) in which the slender piercers (mandibles and first maxillae) See also:

• WORK

work to and fro . This second pair of maxillae (or labium) form then the hinder or lower boundary of the mouth . In front or above the mouth is bounded by the labrum, while the mandibles and first maxillae lie on either side of it . A median process, known as the hypopharynx or tongue, arises from the See also:

• FLOOR (from O. Eng. flor, a word common to many Teutonic languages, cf. Dutch vloer, and Ger. Flur, a field, in the feminine, and a floor, masculine)

floor of the mouth in front of the labium, and becomes most variously developed or specialized in different insects . The salivary duct opens on its hinder See also:

• SURFACE

surface . It does not appear to represent a pair of appendages, but the maxillulae of the Aptera become closely associated with it . According to the view of R . Heymons, the hypopharynx represents the sterna of all the See also:

• JAW (Mid. Eng. jawe, jowe and geowe, O. Eng. cheowan, connected with " chaw " and " chew," and in form with " jowl ")

jaw-bearing somites, but other students consider that it belongs to the mandibular and first maxillary segments, or entirely to the segment of the first maxillae .

See also:

• NECK (O. Eng. hnecca; the word appears in many Teutonic languages; cf. Dutch ride, Ger. Nacken; in O. E. the common word was heals; cf. Ger. Hals)

Neck.—The head is usually connected with the thorax by a distinct membranous neck, strengthened in the more generalized orders with small chitinous plates (cervical sclerites) . These have been interpreted as indicating one or more primitive segments-between' the head and thorax . Probably, however, as suggested by T . H . See also:

• HUXLEY, THOMAS HENRY (1825–1895)

Huxley (Anat . Invert . Animals, 1877), they really belong to the labial segment which has not become completely fused with the head-capsule . It has been shown by C . See also:

• JANET, PAUL (1823—1899)

Janet (1889), from careful studies of the musculature, that the greater part of the head-capsule is built up of the four anterior head-segments, the hindmost of which has the mandibles for its appendages, and this conclusion is in the main supported by the See also:

• RECENT

recent work on the head skeleton of J . H . Comstock and C . Kochi (1902) and W .

A . See also:

• RILEY, JAMES WHITCOMB (1853– )

Riley (1904) . Thorax . The three segments which make up the thorax or fore-trunk are known as the prothorax, mesothorax and metathorax (see fig . 3) . The dorsal area of the prothorax is occupied by a single sclerite, the ptonotum (fig . 3, d), which is large and conspicuous in those insects, such as cockroaches, bugs (Heteroptera) and beetles, which have the prothorax See also:

• FREE

free--i.e. readily movable on the segment (mesothorax) immediately behind—smaller and of less importance where the prothorax is fixed to the mesothorax, as in bees and flies . The dorsal area of the mesothorax, and also of the metathorax, may be made up of a series of sclerites arranged one-behind the other —prescutum, scutum, scutellum and post-scutellum (fig . 3, e, f, g, h)'the scutellum of the mesothorax being often especially conspicuous . Ventrally, each segment of the thorax has a sternum with which a median pre-sternum and paired episterna and epimera are often associated (see figs . 3, 4) . The recent See also:

• SUGGESTION

suggestion of K .

W . Verhoeff (1904) that the hexapodan thorax in reality contains six primitive segments is entirely without embryological support . Legs.—Each segment of the thorax carries a pair of legs . In most insects the See also:

• LEG
• LEG (a word of Scandinavian origin, from the Old Norwegian leggr, cf. Swed. lagg, Dan. laeg; the O. Eng. word was sceanca, shank)

leg is built up of nine segments: (I) a broad triangular, sub-globular, conical or cylindrical haunch (coxa) ; (2) a small trochanter; (3) an elongate stout thigh (femur); (4) a more slender shin (See also:

• TIBIA

tibia) ; and (5-9) a See also:

• FOOT

foot consisting of five tarsal segments . The fifth (distal) tarsal segment carries a median adhesive See also:

• PAD

pad—the pulvillus—on either side of which is a claw . The pulvillus is lbr A From See also:

• MIALL, EDWARD (1809-1881)

Miall and Denny, The Cockroach, See also:

• LOVELL, FRANCIS LOVELL, VISCOUNT (1454-1487)

Lovell See also:

• REEVE (O. E. gerefa)
• REEVE, CLARA (1729–1807)
• REEVE, HENRY (1813–1895)

Reeve & Co . probably to be regarded as a true terminal (tenth) segment of the leg, while the claws are highly modified bristles . Numerous bristles are II - IV Sifter Marian, See also:

• FAT (O.E. fdett; the word is common to Teutonic languages, cf. Dutch vet, Ger. Fett, &c., and may be ultimately related to Greek Irian, and =apos, and Sanskrit pivan)

Fat . Bull . 3, n. s . (U.S . Dept .

Agr.) . I, Dorsal view. d, Pronotum . 1, Coxa of middle leg . II, Ventral view . Mesothorax: Metathorax: IV, Lateral view with f, Scutum. o, Epimeron . segments separated. g, Scutellum. p, Coxa of hind leg . Prothorax: h, Post-scutellum. n, First Abdominal a, Episternum. i, Mesophragma . Segment . b, Sternum. j . Epimeron. t, See also:

• TEGULA

Tegula at base of c, Coxa of fore-leg. k, Episternum. fore-wing. usually present on the thighs, shins and feet of insects, some of them so delicate as to be termed " hairs " others so stout and hard that variety, dependent on the order to which the insect belongs, and the See also:

• SPECIAL

special See also:

• FUNCTION

function—walking, See also:

• RUNNING

running, climbing, digging or See also:

• SWIMMING (from " swim," A.S. swimman, the root being common in Teutonic languages)

swimming—for which the limb is adapted . The walking of insects has been carefully studied by V . Graber (1877) and J .

Demoor (189o), who find that the legs are usually moved in two sets of three, the first and third legs of one side moving with the second leg of the other . One See also:

• TRIPOD (Gr. rpiTovr, Lat. tripus)

tripod thus affords a firm base of support while the legs of the other tripod are brought forward to their new positions . Wings.—Two pairs of wings are present in the vast majority of insects, See also:

• BORNE, KARL LUDWIG (1786–1837)

borne respectively on the mesothorax and mtathorax . At the base of the wing, i.e. its See also:

• ATTACHMENT

attachment to the trunk, we find a ,highly complex series of small sclerites adapted for the varied movements necessary for flight . Those of the See also:

• DRAGON (Fr. dragon, through Lat. draco, from the Greek; connected with SEpeoµay " see," and interpreted as " sharp-sighted "; O.H. Ger. tracho, dracho, M.H.G. trache, Mod. Ger. Drachen; A.S. draca, hence the equivalent English form " drake," " fire-drake,

dragon-flies (Odonata) have been described in detail by R. von Lendenfeld.(1881) . The long See also:

• AXIS (Lat. for " axle ")

axis of the wings, when at See also:

• REST (O. Eng. rest, reste, bed, cognate with other Teutonic forms, e.g. Ger. Rast, Riiste, rest, and probably Gothic Rasta, league, i.e. resting or stopping place)

rest, lies parallel to the body axis . In this position the outer margin of the wing is the See also:

• COSTA, GIOVANNI (1826–1903)
• COSTA, LORENZO (146o-r535)
• COSTA, SIR MICHAEL ANDREW AGNUS (1808-1884)

costa, the inner the dorsum, and the hind-margin the termen . The See also:

• ANGLE (from the Lat. angulus, a corner, a diminutive, of which the primitive form, angus, does not occur in Latin; cognate are the Lat. angere, to compress into a bend or to strangle, and the Gr. ayKOS, a bend; both connected with the Aryan root ank-, to

angle between the costa and termen is the apex . When the wing is spread, its long axis is more or less at a right angle to the body axis . A wing is an out-growth from the dorsal and pleural regions of the thoracic segment that bears it, and microscopic examination shows it to consist of a See also:

• DOUBLE
• DOUBLE (from the Mid. Eng. duble, the form which gives the present pronunciation, through the Old Er. duble, from Lat. duplus, twice as much)

double layer of cuticularized skin, the two layers being in contact except where they are thickened and folded to form the firm tubular nervures, which serve as a supporting framework for the wing membrane, enclose air-tubes, and convey blood . These nervures consist of a series of trunks radiating from the wing-base and usually branching as they approach the wing-margins, the branches being often connected by See also:

• SHORT, FRANCIS JOB (1857– )

short transverse nervures, so that the wing-area is marked off into a number o: " See also:

• CELL (from Lat. cella, probably from an Indo-European kal —seen in Lat. celare, to hide; another suggestion connects the word with Lat. cera, wax, taking the original meaning to refer to the honeycomb)

cell§ " or areolets . The details of the nervuration vary greatly in the different orders, but J .

H . Comstock and J . G . Needham have lately (1898-1899) shown that a See also:

• COMMON

common arrangement underlies all, six series of See also:

• LONGITUDINAL

longitudinal or radiating nervures being present in the typical wing (see fig . 5) . Along the costa runs a costal nervure . This is followed by a sub-costal which some-times shows two main branches . Then comes the radial—usually the most important nervure pf the wing—typically with five branches, and the median with four . These sets arise from a main trunk towards the front region of the wing-base . From another hinder trunk arise the two-branched cubital nervure and three See also:

• SEPARATE

separate anal nervures . In the hind-wing of many insects the number of e radial branches becomes re- duced, while the anal area is After See also:

• QUAIL (0. Fr. Quaille, Mod. Fr. Caille, Ital. Quaglia, Low Lat. Quaquila, Du. Kwakkel and Kwartel, Ger. Wachtel, Dan. Vagtel)

Quail . Natural See also:

• SCIENCE (Lat. scientia, from scire; to learn, know)

Science, vol. xiii., especially well developed and J.-M .

Dent & Co . undergoes a See also:

• FAN (Lat. vannus; Fr. eventail)

fan-like folding FIG . 5.—Wing-Neuration in a when the wings are closed . Cossid See also:

• MOTH

Moth . 2, sub-costal; 3, Great diversity exists in the radial; 4, median; 5, cubical', texture and functions of fore 6 7, 8, anal nervures . and hind-wings in different in- ' sects; these See also:

• DIFFERENCES, CALCULUS OF (Theory of Finite Differences)

differences are discussed in the descriptions of the various orders . The wings often afford secondary sexual characters, being not infrequently absent or reduced in the female when well developed in the male (see fig . 6) . Rarely the male is the wingless See also:

• SEX (Lat. sexes; possibly connected with secure, to cut)

sex . In addition to the wings there are smaller dorsal outgrowths of the thorax in many insects . Paired erectile plates (patagia) are borne on the prothorax in moths, while in moths, sawflies, wasps, bees and other insects there are small plates (tegulae)—see Fig . 3, t—on the mesothorax at the base of the fore-wings .

Abdomen.—In the abdominal exoskeleton the segmental structure is very clearly marked, a series of sclerites—dorsal terga and abdominal sterna—being connected by See also:

• PALE (through Fr. pal, from Lat. palms, a stake, for paglus, from the stem pag- of pangere, to fix; " pole " is from the same original source)

pale, feebly chitinized cuticle, so that considerable freedom of movement between the segments is possible . The first and second abdominal sterna are often suppressed or reduced, on account of the strong development of the hind-legs . In many insects ten, and in a few eleven, abdominal segments can be clearly distinguished in addition to a small terminal anal segment . The female genital opening usually lies between the seventh and eighth segments, the male on the ninth . Prominent paired limbs are often borne on the tenth segment, the elongate tail-feelers (cerci) of bristle-tails and may-flies, or the forceps of earwigs, for example . In the Embiidae, a See also:

• FAMILY

family of Isoptera, it has been shown by G . Erfderlein (1901) that these cerci clearly belong to a partially suppressed eleventh segment, and R . Heymons (1895-1896) has proved by embryological study that in all cases they really belong to this eleventh segment, which in the course of development becomes fused with the tenth . Smaller appendages (such as the stylets of male cockroaches) may be carried on the ninth segment . Pairs of processes carried on the eighth and ninth segments often become specialized to form the ovipositor of the female (see €[g . 14) and the genital See also:

• ARMATURE (from Lat. armatura, armour)

armature of the male . A marked modification of the hinder abdominal segments may be noticed in most insects, After Miall and Denny, The Cockroach, Lovell Reeve & Co .

I, Fore-leg and See also:

• PRO

pro-sternum (S) ta, Tarsal segments . in front of which are the II, Middleleg and mesosternum. ventral cervical sclerites III, Hind leg and metasternum . (c) . In IIIa, the episternum (a) and cx, Coxa. tr, Trochanter. epimeron (See also:

• BARE

bare slightly separ- fe, Thigh. lb, Shin. ated . they are named " spines " or " spurs." In the relative development and shape of the various segments of the leg there is almost endless From Miall and Denny, The Cockroach, Lovell Reeve & Co .