Summer officially ends this weekend, but the cicadas are still making a raucous sound in my garden. Much of what we know about this summer songster is thanks to the work of a hero of New Zealand science

Cicadas are as much a mainstay of a New Zealand summer as the sound of surf and a game of cricket. We go to sleep listening to their song while children collect their intricate shells. But how much do we actually know about our fair-weather friends?

Those cicada shells that children like to collect, for example, are actually the shells of the cicada nymph, which is what the youngsters of the species are called. According to John Marris’s article on cicadas on Te Ara, the female cicadas lay their eggs on plant tissues such as leaves, grass, or twigs. When the wingless cream-coloured nymphs emerge from the eggs, they burrow deep into the ground, where they survive by sucking juices from the roots of trees. The nymphs live underground for several years, undergoing several moults, before they reach maturity. Under cover of darkness, the mature nymphs leave the ground, climb a nearby tree trunk or post, and shed their skin for the last time, emerging as an adult winged insect ready for flight. In contrast to the years the cicadas spend in the nymph stage, they spend only weeks in the winged stage, during which time they feed on sap, mate, lay eggs (the females) and make a lot of noise (the males).

Much of what we know about cicadas comes from research done by Charles Fleming in the 1960s. Fleming, born in Auckland in 1916, was one of New Zealand’s last great naturalists, a real scientific polymath. He trained as a geologist, but also published papers and books on ornithology, conchology, palaeontology, entomology and biogeography, and was an advocate for conservation of New Zealand’s forests and birds. In her biography of her father, Charles Fleming: Environmental Patriot, Mary McEwen describes Fleming’s cicada research. Fleming’s childhood cicada interest involved collecting, preserving and identifying species of the fully-fledged insect (rather than the crude nymph shell collecting most children indulge in) but he revived his interest in cicadas as an adult, enlisting the help of his wife and daughters. As Mary described it, “cicadas dominated weekend activities in Wellington and Waikanae, where many witnessed the Flemings wielding butterfly nets on long metal handles or creeping up on singing cicadas with tape recorder and microphone in hand”. To many of us, cicada song can seem like an annoying racket that starts way too early in the morning, but Fleming used the slight variations in cicada song to identify many different species. There are now 42 known cicada species and subspecies identified in New Zealand, many of which are illustrated on Landcare Research’s cicada identification guide.

So what's all that noise for? The male cicadas “sing” to attract females. They produce their distinctive sound using ribbed membranes, called tymbals, on each side of the base of the abdomen. As Marris describes it, “Each tymbal is attached by a tendon to a powerful muscle. As the muscle contracts it buckles the shape of the tymbal, much as when the domed lid of a jar is first unsealed, causing a burst of sound called a pulse. When the muscle is relaxed the tymbal pops back into shape. Rapid and repeated muscle contraction produces the distinctive cicada call.” The range of distinctive sounds the different cicada species can make depends on the tymbal shape, the rate and pattern of pulsing and, of course, the volume. I like the Maori name for New Zealand’s most common and loudest cicada species, the chorus cicada: the wawa in the name kihikihi wawa means “to roar like the sound of heavy rain”.

Cicadas were in the news last weekend when an Auckland man made a fuss after finding a cicada in his Macdonald’s fries. He declined to eat his deep fried cicada, but on the West Coast they pay for the privilege. I’ve never eaten them, but cicadas make regular appearances on the menu at Hokitika’s Wild Food Festival (coming up this March). Cicada and pistachio ice cream anyone?

So keep an eye on those discarded nymph shells in your back yard – once you notice the last ones it will be only two or three weeks until the cicada song ends for the year. But if you think you’ll miss the sound of cicadas come the end of summer, you can always listen to Charles Fleming introducing the songs of the sand dune and red-tailed cicadas on Te Ara.