By Dr Sue Jaggar, UNE Discovery

Summer is here and the air is filled with the sound of summer, cicadas. They are the loudest insects in the world, and can have a volume up to 120 decibels (similar to a chain saw or motor cycle). Little is known of the Australian species, but there are an estimated 500-800 species in Australia, or possibly even more.

Cystosotoma saundersii is a Bladder Cicada, photo taken in Botany garden UNE

Kobonga umbrimargo is an Orange Clicker, photo taken in Forrestfield, WA

Popplepsalta notalis is a Southern Red-eyed squeaker at Mole Station, Tenterfield

Adult cicadas lay eggs in slits in plant stems, or under bark. They hatch and drop to the ground, digging into the soil and feeding on plant roots. Their life as a nymph (their immature stage before becoming an adult) can be up to 7 years for Australian species, and 17 years for some of the American species. While underground they moult through a series of instars, getting larger each time. Instar is the name given to the developmental stage of an arthropod between moults.

When conditions are right (generally regulated by temperature and their internal clock, and other unknown factors), and they have developed, they emerge from the soil, climb onto a plant and moult for a final time. The photos show an emerging Yotetta ignita (Fiery Ambertail) which is common in the New England Region. The wings are inflated with a fluid (called hemolymph) and their body hardens.

Photo collage shows a cicada undergoing its final moult

Yotetta ignita with wings open in Armidale