Where have all the cicadas gone?

That's the question bugging some RNZ listeners, who say instead of New Zealand's iconic summer chorus, all they've heard from forests and fields so far this year is silence.

'Bugman' Ruud Kleinpaste tells RNZ Afternoons host Jesse Mulligan a lack of cicadas in some areas was likely linked to the insect's life cycle.

Ruud says he had not heard any cicadas this summer until a few days ago in the Port Hills near Christchurch, and then it was only one or two.

"And to be quite honest, it doesn't surprise me sometimes. Five years ago I wrote in my diary there weren't many cicadas that year either."

The reason it was not surprising was that cicadas - depending on the species - generally had a lifecycle, from egg to egg or larva to larva, of three or five years.

"Which means that if five years ago there weren't very many parents, this year there won't be many juveniles that can come out of the ground.

"It's the same as happens in America with their 17-year cicada and 13-year cicada," he says.

"They come in waves, and those waves are pretty determined by the calendar."

Ruud says New Zealand had more than 40 species of cicada.

Each lived in a different environment, had a different lifecycle and fulfilled a different ecological role.

Some listeners also reported hearing fewer crickets, which usually took over the chorus from cicadas once night fell. That was backed up by an unscientific poll of RNZ staff.

Ruud says he could not verify that because he lived in Canterbury and black field crickets were limited to northern New Zealand.

However, if correct, the drop in cricket numbers would have a different cause.

"That's because they have a one-year life cycle.

"They basically get out of the eggs in October or November, go out at night and eat the grass in the paddocks and lawns, and then by January, they become adults and start making these mating calls.

"There's no cycle of three or five years."

If crickets were in decline, that would not worry the Bugman.

"They are not native, they are introduced, and they are actually pests for farmers.

"Ten crickets per square metre is the same as one stock unit in terms of the amount of grass they eat."

Jesse tells Ruud his favourite bug find of the year - discovered by his son on the kitchen floor, prompting great excitement in the household - was a giant New Zealand centipede.

Jesse describes it as a beautiful creature, but Ruud says it was one of the very few invertebrates he was not fond of.

"I was bitten once by a centipede in Auckland.

"I was paralysed for two-and-a-half hours on my right hand.

"They have no sense of humour.

"They are incredibly aggressive when you grab them.

"Don't touch them."

However, the giant centipede had some remarkable abilities.

Ruud says the female laid its eggs in a rotting log, then licked each egg every 20 to 30 minutes to remove bacteria and fungi.

If the centipede was disturbed and abandoned its eggs, they would rot within an hour.

He says the creature's saliva must contain an as-yet undiscovered substance with powerful antifungal and antibacterial properties.

"We could have something really cool here," he says.

Ruud says the best thing anyone could do for insects around their property - be they cicadas or giant centipedes - was to boost biodiversity.

"Put as many native plants as you can in your garden, as well as plants that give you flowers for the native pollinators and birds.

"Literally everything starts with insects, those lowly creatures that people love to hate sometimes."

- RNZ