THORAX OF PERIPLANETA
1) Thorax is the second tegmata of the body of cockroach.
2) It consists of three segments namely, prothorax,mesothorax and metathorax.
3) Each segment is covered by four sclerites,
A dorsal- tergum,
A ventral – sternum and
Two lateral – pleura.
4) The dorsal sclerites or terga of the thorasic segments are called pronotum, mesonotum and metanotum respectively.
5) The pronotum is roughly triangular and is the largest sclerite on the body of cockroach.
6) Mesonotum and metanotum are roughly rectangular.
7) Thorax bears three pairs of jointed legs, two pairs of wings and two pairs of large spiracles
LEGS
1) Three pairs of legs are articulated with the pleura and sterna of the thorasic segments.
2) Each leg is made upof five main podomeres.
3) The different podomeres from the base to the tip are
A. COXA-Is the first podomere. It is stout, broad and muscular.
B. TROCHANTER– Is the second podomere.It is the smallest podomere.Triangular in shaped and movably articulated to the coxa.
C. FEMER – Is the third podomere.It bears immovable bristles.
D. TIBIA – It is the fourth podomere. It also bears immovable bristles .
E. TARSUS – Is the last podomere. It is made of five segments. These segments of tarsus aie called tarsomeres. The last tarsomere is called pretarsus. The pretarsus bears a pair of claws .A chitinous spongy pad called pulvillus or arolium is present between the claws. Minute pads called plantulae present on the inner edges of the first four tarsomeres.
4) Arolium and claws help in locomotion on rough surfaces.
5) Plantulae are useful in locomotion on smooth surfaces.
6) The striated muscles help the cockroach to move he legs.
WINGS:-
1) Two pairs of wings are present in cockroach. The first pair on the mesothorax and the second pair on the metathorax.
2) The fore wings are thick and they do not help in flight,but only cover and protect the hind wings when the insect is not flying.these forewings are called tegmina.
3) The hind wings are thin and they help in flight.
4) The wings are supported by a network of fine sclerotised tubes called veins or nervures. Haemolymph, nerves and tracheae enter the nervures of wings.
5) Wings are moved by the dorsoventral and longitudinal muscles.
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