ODONATA
Etymology
:
Odon - tooth
Common names
:
Dragonflies and damselflies
Characters
Medium to large sized insects
They are attractively coloured
Head is globular and constricted behind into a petiolate neck.
Compound eyes are large.
Three ocelli are present
Mouthparts are adapted for biting. Mandibles are strongly toothed Lacinia and galea are
fused to form mala which is also toothed.
Wings are either equal or sub equal, membraneous; venation is net work like with many
cross veins. Wings have a dark pterostigma towards the costal apex. Sub costa ends in
nodus. Wing flexing mechanism is absent.
Legs are anteroventrally placed. They are suited for grasping, holding and conveying the
prey to the mouth. Spinose femora and tibiae are useful for holding the prey. Forward shift
of leg attachments allow easy transfer of prey items to mouth in flight. Legs are held in
such a way that a basket is formed into which the food is scooped.
Abdomen is long and slender. In male gonopore is present on ninth abdominal segment.
But the functional copulatory organ is present on the second abdominal sternite. Before
mating sperms are transferred to the functional penis. Cercus is one segmented.
Metamorphosis is incomplete with three life stages. The naiad is aquatic. Labium is greatly
elongated, jointed and bears two hooks at apex. It is called mask. It is useful to capture the
prey.
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