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I. A surface, with supportII. Some sort of articulation mechanismIII. Muscles to power the surface (more later)IV. Mechanisms to generate lift

• Passive mechanisms• Tilt• Twist• Camber

• Active mechanisms

III

III

III & IV

co-opted from leg base

Tricks for generating lift:

Fast-flying birds(from side & top):

Slow-flyingbirds (side

& top):

Path of wing tip

Complex wing motion(active & passive mechanisms)

Drosophila (Diptera)

Muscidae (Diptera): red = top surface, blue = bottom surface

Odonata: Anisoptera

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Tracing the path of wing motion in Hymenoptera

hovering flight

backwardsflight

forward flight

Changes in orientation ofbody axis changes in flight

Compare with hovering flightin a bird:

Ephemeroptera

PlecopteraSialidae

Mecoptera Trichoptera

FulgoroideaMuscidae

Coleoptera

Hemerobiidae

Plecoptera

Sisyridae

Symphyta

= path offore wing

= path ofhind wing

body axis

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Clap & fling (also clap & peel, etc.)

Closing dorsally(upstroke)

Opening dorsally(downstroke)

1 2 3 4

1 2 3 4

anterior

leading edgeof wing

leading edgeof wing

posterior

axial view

anterior

posterior

axial view

(peel)

(clap)

Major wing regions:Remigium, Vannus/Anal area/Clavus, and Jugum

a = axis of rotation (torsion)b = axis of massc = axis of aerodynamic pressure

pterostigmaarea of

articulation

Jugum RemigiumVannus

anal suture

“Ground Plan” of insect wing:• relatively large size

• isopterous in structure & venation

• half as broad as long

• smooth membrane: semi-transparent, little pigmentation, and a few small hairs on veins

• complete complement of veins

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Changes in the proportions of remigium vs. vannus

area ofarticulation

Orthoptera: Acrididae

jugal area(jugum)

analarea

remigium

anal suture

(also called vannus or clavus)

remigium remig.

anal area(fan)

lines of axial folding

folds of “fan”anal area

(fan)

anal area

Generalized condition: archaic Insecta

Coleoptera: Staphilinidae

Coleoptera

Blattodea

Orthoptera

coriaceous texture

elytron

Hemiptera: Heteroptera

hemelytron

anal fan(vannus)

Front wing/back wing

differences: size & texture

anal fan

coriaceousmembrane

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Other color & textural changes: hairs (setae) and scales

Trichoptera

Lepidoptera

Hairs & scales:

• protection

• smoothing of air flow

• sensing air movements

Colors:

• aposematic

• thermoregulation

• crypsis & mimicry

• courtship & mating

elytron

Dermaptera

Diptera

Front wing/back wing

differences:

extreme specialization

haltere

resilin

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More front wing/ back wing

differences:

Tails

Neuroptera: Nemopteridae

Lepidoptera: Papilionidae

Likely function: protection by predator distraction

Front/back, left/right, & sex differences: strigils

male (left = right) female female

male

leftright

≠

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Jugal specializations and wing coupling mechanisms

by a jugum: Hepialidae by a frenulum: Psychidae

by hamuli: Hymenoptera retinaculum

humeral lobe

frenulum

jugum

hamulus

radialvein

(ventral views)

Wing coupling mechanisms, magnified

Frenulum in aganaid moth

Hamuli in wasps

retinaculum

(classified as “frenate moths”)

frenulum

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Pterostigmata

Odonata: Anisoptera

Neuroptera: Ascalaphidae

Hemiptera: Aphidae

Functions:• flexible tip for aerodynamics

• flexible tip for clap & peel

• fluid-filled counterweight to prevent “stalling”

• other unknown advantages

Independently evolved many times

pterostigma

Insect wing venation: ancestral archedictyon

(an “ancient net”)

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Importance of wing venationfor classification & phylogenetic analysis:

1. Single origin of wings: interpretations can be based on the assumption of monophyly & real homology

2. Conservative evolution: venation changes slowly so phylogenetic signal remains intact over long time periods

3. Provides a set of characters shared by nearly all insects

4. Nicely preserved in the fossil record -- often, only wings are present (like leaves of extinct plants)

C+ Sc-R+

Rs-

MA+

MP-

CuA+CuP-

1A+2A+3A+

R+M-

Cu+

Sc1 Sc2

R1

Rs1

Rs2

Rs3

Rs4

MA1

MA2

MP1

MP2

MP3MP4CuA1CuA2

Interpreting wing venationin modern insects

Major wing veins:Costa (C) (+)

Subcosta (Sc) (–)

Radius (R) (+)

Radial Sector (Rs) (–)

Anterior Media (MA) (+)

Posterior Media (MP) (–)

Anterior Cubitus (CuA) (+)

Posterior Cubitus (CuP) (–)

Anal (A) (+)

Interpreters:- Redtenbacher

- Hagen (mid-1800s)

- Comstock &

Needham (1918 book)

CONVEXITY (+)

CONCAVITY (–)

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Major wing veins:Costa (C)Subcosta (Sc)Radius (R)Radial Sector (Rs)Anterior Media (MA)Posterior Media (MP)Anterior Cubitus (CuA)Posterior Cubitus (CuP)Anal (A)

A more detailed view of wing venationpterostigma

axill

ary

scle

rite

s

Homologizing wing veins: the pretracheation theory

AB

cross-over

R

ScCWING

RADIUS

Rs

1ARs+CuA

(Cu1)

CSc

RRs r

s

M1

M2Cu1Cu21A2A

3A

B

RADIUS (+)

Rs (-)MA (+)

Comstock & Needham;“Cornell (U.S.) school”

of venation.

John Henry Comstock

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Alternatives to the pretracheation theory(“European school” of wing venation – Tillyard, esp.)

Tracheae grow into pre-existing “lacunae”(Holdsworth 1937)

Homologizing wing veins:Convexities and concavities (Martynov & Lameer, 1930s)

tracheal branch nerve“lacuna”

cuticular surfaces

convex veins

concave veinscuticular layers

C(+) R(+) MA(+) CuA(+) 1A(+)

Sc(–) Rs(–) MP(–)CuP(–)

(separation using KOH-- Holdsworth’s method)Exceptions (too specialized, or flattened):

• tegmina & elytra• mid-section of holometabolous wing

Robin John Tillyard

Neuroptera: Chrysopidae

Hymenoptera: Chalcidoidea

Thysanoptera

Odonata: Anisoptera

ColeopteraHemiptera: Heteroptera

cross-vein

marginal twigging

one vein

one vein

setae

pterostigma

nodusarculus

elytron

hemelytron

Proliferation:

Reduction:

Special functions: