Odonata species start their life as aquatic larvae, passing through a series of developmental stages or ‘stadia’ and undergoing several moults as they grow. Before the final moult (emergence), metamorphosis occurs in which the larvae transform into the adult form. Adults complete their metamorphosis after emergence and undergo a pre-reproductive phase known as the maturation period, when individuals normally develop their full adult colour (5) (7). Nothing has been recorded of the Bulgarian emerald’s social, reproductive or feeding behaviour, but certain details can be inferred from what is known about Somatochlora meridionalis, which occurs in the same habitat in the same area, and its western counterpart, S. metallica. Eggs would hatch four to ten weeks after deposition. The larval period would extend over two or three years and would involve 12 or 13 stadia. Larvae would live at the surface of the sediment and within leaf litter detritus accumulated at the bottom of the river. The so-called territorial behaviour of many Somatochlora species remains controversial and poorly depicted. After copulation, which occurs at variable distances from the banks and generally in tree crowns, Bulgarian emerald females return to the river to lay their eggs in calm, shaded areas, unaccompanied by the male (6).
Odonata feed on flying insects and are often generalised, opportunistic feeders, sometimes congregating around abundant prey sources such as swarms of other insects (7).