Insects of the family are large to very large sized dragonflies and the number of member of known species reach to over 400 worldwide. The head with two large compose eyes, which are usually brighten green or blue in life, touching together as a line, the labia with weak permental cleft. The thorax is healthy and strong, often green or blue coloured with yellow marking. The wings are usually hyaline but in some species, they are suffused with smoky ochreous colour. Wings of males are, in many species, angulated at the base, the triangles of fore and hind wing are homologous, the 1A vein is pectinate basally. Their abdomen is long and commonly coloured marking. There usually are auricles on both lateral sides of the segment 2 and constricted at the segment 3 of the abdomen. The anal appendages are often long with fasten inferiors. The females possess well developed ovipositors with which they insert their eggs into plant tissue, moss on wet rocks, debris or tree trunks. Many species of the family are crepuscular or even partly nocturnal and some of them are attracted by the lights at night. Larvae are elongate and smooth with their labia long and flat; and they spend their time climbing among the jungle of water plants. They are found in stranding waters, backwaters of running streams or marshy waters with dead leaf layers.
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Anax immaculifrons Rambur, 1842 photographed by Cuong Do, Bach Ma National Park, Thua Thien Hue
Polycantha erythromelas (McLachlan, 1896), the female is laying her eggs, hotographed by Cuong Do, Tam Dao National Park
Tetracanthagyna waterhousei McLachlan, 1898, male in dorsal view, photographed by Cuong Do, Quang Binh Province
Tetracanthagyna waterhousei McLachlan, 1898, male in lateral view, photographed by Cuong Do, Quang Binh Province
Tetracanthagyna waterhousei McLachlan, 1898, close up of male anal appendages in dorsal view, photographed by Cuong Do, Quang Binh Province
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