Cicadas are singing in good numbers in our organic olive groves. A land management that is sympathetic to wildlife delivers tangible results.
Only males produce the characteristic sound. Male cicadas have a resilin structure called a tymbal below each side of the anterior abdominal region. The tymbals are structures of the exoskeleton formed into complex membranes with thin, membranous portions and thickened ribs. Contraction of internal muscles buckles the tymbals inwards, thereby producing a click; on relaxation of the muscles, the tymbals return to their original position, producing another click. The male abdomen is largely hollow, and acts as a sound box. By rapidly vibrating these membranes, a cicada combines the clicks into apparently continuous notes, and enlarged chambers derived from the tracheae serve as resonance chambers with which it amplifies the sound. The cicada also modulates the song by positioning its abdomen toward or away from the substrate. Partly by the pattern in which it combines the clicks, each species produces its own distinctive mating songs and acoustic signals, ensuring that the song attracts only appropriate mates.
Two cicada species live in our olive groves. The smaller one is Cicada orni, while the larger one is Lyristes plebejus, which also sings louder.
After mating, the female cuts slits into the bark of a twig where she deposits her eggs. When the eggs hatch, the newly hatched nymphs drop to the ground and burrow. Cicadas live underground as nymphs for most of their lives at depths down to about 2.5 metres. Nymphs have strong front legs for digging and excavating chambers in close proximity to roots where they feed on xylem sap. In the final nymphal instar, they construct an exit tunnel to the surface and emerge. They then moult (shed their skins) on a nearby plant for the last time, and emerge as adults. The exuviae or abandoned exoskeletons remain, still clinging to the bark of the tree.
Their life cycle that lasts approximately 4-5 years, tough they spend as adult only a month and a half. Adults drink plant sap utilizing their sucking mouthparts.
Cicadas are an important prey item for many species living in and around our olive groves, including the scops owl, the European roller, the woodchat shrike and the western green lizards.