1

The insect leg(generalized Orthoptera)

leg of Weta

3. femur

4. tibia

2. trochanter

6. pretarsus

1. coxa tendencytowardfusion

tendency towardfusion with thorax

plantulae

Significance ofmultiple tarsomeres:

1 5 1

5. tarsus (with 4 tarsomeres)

male Aukland Tree Weta

1 24

3

Leg modifications

Unspecialized (homonomous)

More specialized(heteronomous)

Plecoptera

Coleoptera(harlequin beetle)

Muscoid Diptera (legless)

2

LOCOMOTION:I. Natatorial legs

Whirligig beetle(Coleoptera: Gyrinidae)

Water boatman(Hemiptera: Corixidae)

Backswimmer(Hemiptera: Notonectidae)

Water strider(Hemiptera: Gerridae)

pretarsustarsus

swimmingblades

tibia

femur

trochanter

coxa

(note “feathering” of tarsi, like oars)

ungues

Caeliferan Orthoptera

Ensiferan Orthoptera

LOCOMOTION:II. Saltatorial

Fleas:Siphonaptera

Hymenoptera: Encyrtidae

Hemiptera: Cicadellidae

tarsus

tibiafemur

trochantercoxa

p.t.

mesothoracicleg

3

Mole cricket(Gryllotalpidae:

order Orthoptera)

Cicada nymph(Cicadidae:

Auchenorrhyncha:order Hemiptera)

Scarab beetle(Scarabaeidae:

order Coleoptera)

LOCOMOTION: III. Fossorial (showing convergence in 3 orders)

tarsus

tarsus

tarsus femur

femur

femur

coxa

coxa

coxa

trochanter

trochanter

trochanter

Mole cricket –Orthoptera:

Gryllotalpidae

Cicada nymph –Hemiptera:Cicadidae

Scarab beetle –Coleoptera:

Scarabaeidae

GRASPING: I. Raptorial(showing convergence in 2 orders)

MantisflyNeuroptera: Mantispidae

Preying mantis(Dictyoptera: Mantodea)

tarsus & pretarsus

tarsus &pretarsus Diving beetle

(Coleoptera: Dytiscidae)

tibiafemur

trochanter

coxa

“eye” spot

prothorax

(partial fusion)

spur

4

More raptorial legs: Hemiptera, Orthoptera, Lepidoptera

Belostomatidae

Hemiptera:Belostomatidae

Hemiptera: Nepidae

Hemiptera:Reduviidae

Orthoptera:Tettigoniidae

Lepidoptera:Geometridae

GRASPING: II. Ectoparasites

An adult muscoid fly, ectoparasitic on bats(fam. Nycteribiidae, Muscoidea, order Diptera)

Pubic louse, ectoparasitic on humans(Anoplura, ‘Phthiraptera,’ Psocodea)

tarsus

tibia

femur

pretarsus

tibialspine

tarsal spur

5

STRIDULATORY legs: Acrididae (Orthoptera)

POLLEN-CARRYING legs in the honey bee, Apis mellifera

coxa

trochanter

femurtibia

pretarsus

tarsus

rake

press

press

corbicula

combs

INNER ASPECT OUTER ASPECT

rake

6

OTHER specialleg modifications

Antenna cleaner(foreleg of honey bee)

Tympanal organ(foreleg of cricket

or katydid)

Female hold-fast organs(foreleg of male ,

a diving beetle)Dytiscus

Tympanalorgans

SENSATION:

tibia

tarsus

femur

coxa

trochanter

coxa

trochanter

femur

suctiondisks

1st tarsal segment (tarsomere)

antenna cleanerspine

ANTENNA CLEANER(foreleg of honey bee)

TYMPANAL ORGAN(foreleg of cricket & katydid

HOLD-FAST ORGANS(foreleg of male Dytiscus,

a diving beetle)

SPINNERETS(foreleg of Embioptera)

tarsomerestibia

silkejectors

SEXUAL DISPLAYS

CRYPSIS, for aggression (tropical mantis: Mantodea)

7

CRYPSIS, for defense (orders Phasmatodea & Lepidoptera)

Hornet clearwing moth (Paranthrene)

Leaf insectStick insect

FALSE legs (prolegs)

Lepidoptera caterpillar

Sawfly larva (Hymenoptera)

Coleoptera larvacrochets

Diptera larva

8

Origin of Insect Wings: Prerequisites

• A flap of reasonable size, positioned amid-ships

• Some sort of articulation, to allow movement

• Muscles to flap it up and down and control the structure

• A pre-existing function for the structure while it is small