Source: Radio New Zealand
Hamilton’s cicada (Maoricicada hamiltoni) is heard in summer in the lower North Island and inland South Island. Tara Hills / Cicadas of NZ
Explainer – Depending on your tolerance, it’s the iconic sound of a Kiwi summer or a drill buzzing into your ears.
The seasonal serenade of cicadas kicks off as the weather warms and typically peaks sometime in February – but how and why do these insects make such a loud noise?
Here’s a primer on how New Zealand’s annual cicada season works.
Why do they make so much noise, anyway?
It all boils down to, they want some love.
Cicadas emerge from the ground – typically from December to March or so – to spend the rest of their brief lives trying to mate. The males make their distinctive buzz as they’re desperately seeking some sweet, sweet cicada loving.
“I love it,” said Julia Kasper, Te Papa’s lead curator of invertebrates. “It’s beautiful, it’s the sound of summer and still very exotic.”
“That’s basically the noise of a wedding. In summer all the adults are emerging from nymphs that live in the soil.”
Cicadas actually spend most of their lives underground. The New Zealand varieties typically live as nymphs for two to three years before shedding their final shells and emerging as adults.
In some parts of the world, what are called periodical cicadas can spend as long as 17 years underground, such as in the eastern United States where trillions of them can burst forth in a single season.
The tymbal, on the cicada’s thorax, is tucked beneath the wings. Sandy Werner
“It’s the males that sing, calling for the females, trying to be the loudest, the coolest, the best and getting, you know, the prettiest girl, and the girls are moving towards the males,” Kasper said.
Of course, not everyone adores the cicada’s call.
“Some people love the sound,” said Professor Grant Searchfield, head of the department of audiology at the University of Auckland.
“(For them it’s) ‘the sound of summer’ so it’s not bothersome at all, but some people may find the sound annoying or are more sensitive to sound.”
A cicada’s song can hit between more than 80 decibels, studies have found.
That’s within the range of “dangerous” sounds as defined by the American Academy of Audiology, which lists power tools, concerts and sporting events as hitting the same benchmarks, where damage can be caused with repeated exposure.
Airplanes can hit more than 120db during takeoff, while gun shots can reach over 150db – well within the range of causing hearing damage.
How does such a small insect make such a huge sound?
These plucky insects come with a built-in amplifier, a special organ called a tymbal.
“It’s amazing and we still know so little about it,” Kasper said.
The “tymbal organ sits in their thorax and it’s basically a drum,” Kasper said. “You can see it from the outside, it’s almost like it looks a bit like a window in their side.”
Many insects make noise by rubbing body parts together, such as crickets, but in the cicada’s case, the tymbal itself contracts and expands, pulling a ribbed membrane back and forth so quickly it can sound to humans like a continuous sound.
“It’s so complex it’s unbelievable,” Kasper said, noting that studies that use video to slow the movement down reveal how intricate the cicada’s song is – and humans may not even be capable of hearing some of the sounds.
Our ears may not always discern it, but every species of cicada also has a different song.
How many cicadas are there in New Zealand? Are they unique to here?
Cicadas are found all around the world, but there are at least 42 distinct species in New Zealand. There’s even a species endemic to Norfolk Island. The most common is the Amphipsalta zelandica, or the chorus cicada.
There’s one species that lives high up in the mountains of the South Island which is the only alpine cicada in the world. It can even freeze and go dormant, Kasper said.
Shells left behind by cicada nymphs from an emerging 17-year cicada brood remain in a tree after being shedded on May 29, 2024 in Park Ridge, Illinois. SCOTT OLSON / AFP
Can some years be louder than others?
How big each year’s cicada eruption is depends on many factors.
“Every year is kind of different,” Kasper said. “The rainfall and the dryness and the humidity. Cicadas need moisture and warmth.
“If it’s too dry they can’t get out of the soil to emerge, and if there’s too heavy rain they’re probably washed off and drowned. It needs to be the right mixture.”
That means every year peak cicada noise might be at a different time.
Are they the loudest insects in the world?
Certain cicadas sure are.
If you’re getting sick of hearing them out on the deck this February, take a moment to be happy you’re not living in the habitat of the African cicada, Brevisana brevis, which can hit 106.7 decibels and has been officially named the world’s loudest insect by Guinness World Records.
Te Papa hosts a wide collection of cicadas in its inventory. Supplied / Te Papa
Can cicadas actually damage your hearing?
“Potentially, but unlikely in reality,” Searchfield said.
“If the cicadas were close enough to the ear, and you couldn’t get rid of them – they were there for hours – it’s possible. But a cicada that close would normally be flicked away.”
“It is unlikely but not impossible that cicadas could cause hearing loss,” he said, but generally the sound is more irritating to some than dangerous.
Still, try to avoid sticking a cicada directly into your ear this time of year, although that’s really pretty good advice any time.
I’m not a fan. Is there anything to do to make them be quieter?
“I never thought of that question because they’re so lovely,” Kasper said.
Still, “I guess you could make your garden very bird-attractive because birds feed on them,” she suggested.
Searchfield said people should avoid turning to earplugs, as they can make you more sensitive to the sound.
“Close the doors and windows, and if you have air conditioning, turn it up – there are sound conditioners, used to drown out noisy city sounds, that could be used,” he said. “I’d suggest trying to think of them as your friendly reminder that the sun’s out.”
But as they say, if you’re particularly bothered by the cicada serenade, all things must pass and the season will end by March or so as the last heartsick male cicadas give up the ghost.
“They only live for two weeks or so (once they come up), they’re only there to mate, and that’s why they sing,” Kasper said.
Until next year, that is, when the buzzy sound of summer will kick off again.
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– Published by EveningReport.nz and AsiaPacificReport.nz, see: MIL OSI in partnership with Radio New Zealand