Type of Insect’s Legs
The insect legs are paired, hollow, more or less cylindrical and jointed outgrowths of the thoracic segments.
A typical leg consists of the following six segments in sequence.
1) Coxa – Coxae
2) Trachanter – Trochanters
3) Femur – Femore
4) Tibia – Tibiae
5) Tarsus – Tarsi
6) Pretarsus – Pretarsi
The Articulation of legs: – The coax articulates with the pleurite at the coxal process and also with the trochantin (articulatory sclerite present near base of coax in primitive insect). The coxal process is situated at the ventral extremity of the pleural suture.
1. The Coxa: It is divisible into coxa-vera (anterior lobe) and meron (posterior lobe)
2. The trochanter: It is most conspicuous and largest segment in many jumping insects.
3. The femur: It is most conspicuous and largest segment in many jumping insects.
4. The Tibia: It is Slender and equals length of femur. Near its distal extremity, carries one or more spurs. In Hymenoptera, the apical and enlarged spur of the anterior tibia fits against semicircular pit of the first tarsal segment through which the antennae are passed and cleaned.
5. The tarsus: In primitive insects it is only one segmented (in Protura & Diplura). But usually it is divided into five segments (tarsomeres). The sub segments do not move independently but only the tarsus as a whole moves.
6. The Pretarsus: Beyond the tarsus, there are several structures collectively known as Pretarsus. Tarsus terminates in a strongly curved claw in Collembola and Protura.
In most insects the claws are paired and between them, on the ventral side, a median unguitractor plate to which flexor muscle of the claws is attached supports the pretarsus. In front of and above this plate the Pretarsus expands into a median lobe or arolium. Among Diptera there are two lobes or pulvilli lying below the claws, often with arolium between them or in place of an arolium, median bristle called empodium.
Log pads (covered with tenant hairs) enable insects to climb smooth and steep surfaces. While claws give grip while walking on rough surface