The document discusses the structure and modifications of insect wings. It describes the different types of longitudinal and cross veins that make up the venation patterns on wings. The document outlines the various wing margins, angles, and regions. It also summarizes different types of specialized wings across insect orders, such as tegmina, elytra, hemelytra, halteres, fringed wings, scaly wings, and membranous wings. Finally, it details different mechanisms of wing coupling in insects, including hamulate, amplexiform, frenate, and jugate systems.

1. Structure and modifications of wing venation,
modifications and wing coupling apparatus
Prepared by
Dr. S. Sumaiya

2. Insect wings
 Two pairs of wings - in pterothoracic segments (meso-
and metathorax)
 Only one pair of wings -eg. true flies (house fly, horse
fly)
 No wings (apterous) – eg. primitive insects (silverfish,
spring tail)
 Secondarily wingless – eg. Head louse, poultry louse
and flea
 Deciduous wings – eg. Ants and termites

3. Wing venation
 The principal veins run more-or-less lengthwise on the wing,
thus called longitudinal veins.
 They are connected by cross-veins.
 A closed area bounded by veins is called a cell.
 In insects, like dragonfly, damselfly, there is an opaque spot
near the costal margin of the wing called pterostigma.
 In more primitive insect groups (Odonata), the regions
between principal veins contain irregular networks of veins.
 These networks represent the remains of the archedictyon
described from insect fossils.
 These veins (and their branches) are named according to a
system devised by John Comstock and George Needham
(1898) - the Comstock-Needham System:

4. Longitudinal veins
• Costa (C) - the leading edge of the wing
• Subcosta (Sc) - 2nd longitudinal vein, typically unbranched
• Radius (R)
- 3rd longitudinal vein, 1-5 branches reach the
wing margin
• Media (M)
- 4th longitudinal vein, 1-4 branches reach the
wing margin
• Cubitus (Cu)
- 5th longitudinal vein, 1-3 branches reach the
wing margin
Anal vein Un branched vein behind the cubitus

5. Cross veins
 Names of crossveins are based on their position relative to
longitudinal veins:
 c-sc : Between the costa and subcosta
 r : Between adjacent branches of the radius
 r-m: Between the radius and media
 m-cu : Between the media and cubitus Some crossveins
have their own name, like
 h : Humeral crossvein
 s : Sectoral crossvein

6. WING MARGINS
Wing is triangular in shape and has three margins and angles.
 Costal margin: Anterior margin is costal margin.
 Apical margin: Outer margin is apical margin.
 Anal margin: Posterior margin is anal margin.

7. WING ANGLES
 Humeral angle: Angle at the base of the costal margin of the
wing.
 Apical angle: Angle between the costal margin and the
apical margin.
 Anal angle: Angle between the apical and anal margin.

8. Wing regions
 The entire body of the wing is divided into basal articular and
alar regions.
 The alar region is divided into three regions -based on the
folding of lines and the concentration of veins.
 Remigium: The anterior area of the wing supported by veins
 Clavus or Vannus: The flexible posterior area is termed as
Vannus
 The two region separated by vannal fold
 Jugum: The proximal part of vannus, when well developed is
separated by jugal fold.
 The area containing wing articulation sclerites – Pteralia is
called axilla

9. Tegmina: Forewings of cockroach,
grasshopper, preying mantis, and earwigs.

10. Elytra : Forewings of beetles and
weevils
• Horny, sclerotized, sheath-like
• Devoid of veins
• During flight, they are kept at an angle

11. Hemelytra: Forewings of heteropteran
bugs
• Basal portion of forewing is thickened and leathery (like elytra)
• Apical/ distal half is membranous
• Wing blade is divided into 5 regions
1. embolium,
2. corium,
3. cuneus,
4. clavus
5. membrane

12. Halteres: Hind wings of true flies
One pair of wing is modified into
‘balancers’.
Provides stability during flight.
Club shaped - has a basal
scabellum, bulbous free end
(capitellum) and a rod like stem.
Scabellum - has 2 large groups of
sensory bodies, forming the smaller
‘Hick’s papillae’ and large set of
scapel plate.

14. Fringed wings: both pairs of
Thrips
• Narrow
• Membraneous
• Margins are clothed with long fine
hairs

15. Scaly wings: both wings of butterflies &
Moths
• Has unicellular flattened
setae, coloured scale like
structure
• Responsible for
colouration of the wing

16. Membranous wings
• Forewing of true flies; hindwing of grasshopper, preying
mantids and beetle; and both wings of dragonflies,
damselflies, bees and wasps
• Wing blade is thin, transparent, supplied with a network of
veins.
• Useful in flight

17. Hairy wings

18. TYPES OF WING COUPLING
 Hamulate : a row of small
hooks – coastal margin of
the hind wing - Hamuli
 Engage the folder posterior
edge of fore wing
 Ex: bees
 Amplexiform: linking
structure – absent
 Coupling achieved by broad
overlapping of adjacent
margins
 Ex: Butterfly

19. TYPES OF WING COUPLING
 Frenate: Fruit sucking
moths and Hawk moths

20. Frenate
 Female frenate:
 Humeral lobe (near the
base of the costal
margin) of the
hindwings gives rise to
a group (2-20 nos.) of
bristles called
frenulum.
 It interlocks with
retinaculum/ catch,
composed of several
forwardly directed
curved hairs on the
cubital vein of the
forewings.
 Male frenate:
 Only a single stout
frenular bristle arises
on the humeral lobe
of the hindwing.
 It interlocks with the
single downward
curved spines of the
retinaculum present
in the radial vein of
the forewing.

21. Jugate: Hepialid moths, Sterpsipterans
 Jugam of the forewings
are lobe like
 It is locked to the coastal
margin of the hindwings