Insect Wings & Legs and their modifications – Free Online Studymaterial

Agricultural Study Materials

The thorax consists of three segments viz., pro, meso and metathorax and each bear onepair of legs called fore, middle and hind legs respectively. Legs are the principal organ oflocomotion and they have undergone many modifications and have been adapted to wide rangeof functions. The generalized insect leg consists of six segments.

1. A basal COXA (articulating with the thorax in the pleural region)

2. A small TROCHANTER

3. A FEMUR (largest part)

4. A TIBIA

5. 1-5 Segmented TARSUS (Pl. Tarsi) 

6. A PRETARSUS (insect foot) and two claws and a pad called arolium

Modification of Insect Legs

1.Ambulatorial.

Walking, segments more or less uniform

Ex – Fore legs and middle legs of grasshopper

2.Cursorial

Walking  and running,  segments  generally long and slender

Ex-Cockroaches

3.Raptorial

Grasping, femur and tibia enlarged with row of spine

Ex – Forelegs of preying mantis

4.Fossorial

Digging, forelegs bearing heavily sclerotized claws adapted for digging soil tarsi digitated

Ex – Fore leg of mole cricket

5.Scansorial

Clinging, tarsus  is one segmented  with a single strong, sickle shaped claw

Ex – Forelegs of head louse

6.Natatorial

Swimming, oarlike, tibia and  tarsus much flattened and fringed with dense hairs.

Ex – Hind leg of water scavenger beetle

7.Saltatorial

Jumping, Femur of the hindlegs are enlarged and  accommodating the muscles used for jumping

Ex.-Hind legs of Grasshopper

8.Clasping legs

Clasping, Tarsus is one segmented and arched, during  reproduction this adaptation enables the male to hold the female

Ex-Foreleg of male water diving beetle

9.Prolegs/ pseudo

legs

Ex-Abdominal legs of lepidopteran larva

10.Foragial

Pollen gathering, Coxa, trochanter and femur are normal in shape, while the tibia of hind leg is dilated and covered with long dense hairs   thus forming a pollen basket or corbicula and meant for storing the pollen grains.

Ex-Hind legs of worker honey bee

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