2. Order: Odonata
Greek "odonto-", meaning tooth
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.
3. Characters
Legs are anteroventrally placed. They are suited
for grasping, holding and conveying the prey to
the mouth.
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.
4. Classification
There are two sub-orders. Dragonflies are classified under Anisoptera and
damselflies are grouped under Zygoptera.
6. Abdominal appendages
Anisoptera : Dragonfly
Male has three abdominal
appendages.
Two superior and appendages (cerci)
and one inferior anal appendage (epi-
proct) are present.
Zygoptera : Damselfly
Four terminal abdominal appendages
are present.
A pair of superior anal appendages
(cerci) and a pair of inferior anal
appendages (paraprocts) are present.
7. Oviposition
Endophytic or Exophytic
Exophytic – in anisoptera, drop the eggs freely into
water or attach superficially to aquatic plants
Endophytic – in zygoptera & two families in anisoptera,
make slits in stems & leaves and insert the eggs