Hemicordulia tau - Tau Emerald

Male identification: A medium-sized dragonfly with a black abdomen, pinched near the base and fringed with orange crescent-shaped marks, the tips of which curve inward. Eyes on mature males are reddish brown and wings are completely transparent and unmarked except for orange leading veins and brown pterostigma. The tip of the tail at segment 10 has a distinctive yellow spot. The face is pale with an inverted T-shape, which gives the species its name.

Female identification: A medium-sized dragonfly with a slightly tapering black abdomen fringed with orange crescent-shaped marks, the tips of which curve inward. Eyes are reddish brown and the leading edge of the wings are suffused with brown and have orange leading veins and brown pterostigma. The tip of the tail at segment 10 has a distinctive yellow spot. The face is pale with an inverted T-shape, which gives the species its name.

Similar species: Similar to H. australiae which differs in having no distinct yellow spot on the tail tip, no T-shaped mark on the face, no orange veins on the leading edge of the wings and a black pterostigma. Differs from P. jacksoniensis which lacks the crescent-shaped marks curving inward over the abdomen.

Behaviour: Flies low over water, hovering stationary for periods and conducting sorties mostly close to the bank but occasionally out across open water. May be seen far from water hawking above head height over bare ground in gardens and parks.

Distribution: Widespread throughout Victoria. Recorded commonly at altitudes less than 600m and also above 1000m, seeming to prefer locations without canopy cover.

Australian State distribution (from CSIRO Entomology)

Habitat: Any standing water.

Status: Common and widespread

Flight period: September to May. Lowland individuals appear to overwinter to emerge early in spring.