Mature orange-spotted emerald males establish territories at favourable breeding sites along a stretch of water, 10 to 20 metres in length, which they patrol continuously, flying back and forth low above the water and banks. Females venturing towards the river are quickly coupled with a male, and mating continues in the heights of the surrounding trees. Females then return to the river to lay their eggs in calm, shaded areas, unaccompanied by the male (9). Males change their territory rather frequently. This reproductive period in which adults are ‘on the wing’ lasts until early August (2) (3) (10).
The eggs hatch two to ten weeks after deposition and the larval period extend over two or three years. The larvae are mostly confined to leaf litter and detritus, accumulated between tree-roots along river banks, where they hunt. The larvae metamorphose into the adult form and emerge as dragonflies mainly in May or June, dependent on the climate. After emergence, the adults undergo a pre-reproductive phase away from the river known as the maturation period, which probably lasts around ten days (7), when they normally develop their full adult colour (11). After this period, they will return to the river to establish their territory.
Adults may feed at any time, but hunt particularly in the evening, when they attack swarms of midges above the river. The night is generally spent in the foliage of surrounding trees (7).