The following people must be thanked for their contributions to this key.
Ben Gunn (CSIRO Entomology), for his contribution of taxa and character
images. Gunther Theischinger (NSW
Environmental Protection Authority), for the loan of many of the specimens that
were used for photography. Richard
Rowe (James Cook University) for providing a specimen of Calopterygidae.
Odonata (dragonflies and damselflies) occur in all types of inland water
except saline lakes. The adults are
winged and can be found near their breeding sites or else (in some species) far
from water. The larvae, with one or
two exceptions, are fully aquatic. The
larval stage lasts from a few weeks to several years, depending on species.
All Odonata are predatory in all life stages.
Species numbers usually are greatest where there is a variety of larval
habitat. A mosaic of stones, mud,
and sand with a complex emergent vegetation yields the greatest range.
Some families occur across a wide range of larval habitat but others are
restricted, eg to streams and torrents, to still or gently flowing water or to
bogs, swamps and seepages. Seventeen
families are recorded from Australia. One
family, several subfamilies, about 60% of genera and 80% of species are endemic.
Damselfly larvae generally are similar to mayfly or stonefly larvae in
overall body proportions. Dragonfly
larvae are stouter and more rounded. Lateral
abdominal gills are never present in the families known from Australia.
Identification to ordinal level is most simply achieved by looking at the
underside of the head: the labium (lower lip) is developed into a large and
obvious mask, hinged at its mid point and terminating in two large palps.
The mask is used as a grasping organ.
It covers the underside and
sometimes also the front of the head. No
other aquatic invertebrate has such a structure although some beetle larvae do
possess a prehensile lower lip.
The two suborders, Zygoptera (damselflies) and Anisoptera (dragonflies)
may be recognised from the caudal structures.
Zygopteran larvae carry three conspicuous appendages (gills) at the tip
of the abdomen: one dorsal, two lateral. Anisopterans
have three small triangular projections in corresponding positions.
Unfortunately, the gills of Zygoptera are rather readily lost or damaged.
Regrown appendages often are of abnormal shape.
However, it rarely happens that all three appendages are lost in the same
specimen except by rough handling post-capture.
Identification to the family level may be based on characters of the
gills and mask together with other external characters.
Small specimens without partially developed wing pads (ie. specimens up
to about instar 6-8, depending on species) may not be identifiable beyond the
Allbrook, P. (1979) Tasmanian Odonata. Fauna of Tasmania Handbook
No. 1. Fauna of Tasmania Committee, Tasmania, Australia.
Hawking, J.H. (1986) Dragonfly larvae of the River Murray system.
Albury-Wodonga Development Corporation Technical Report No. 6., Wodonga.
Watson, J.A.L. and O’Farrell, A.F. (1991) Odonata. pp. 294-310.
In: CSIRO, Insects of Australia. Melbourne University Press,