Australia Weather News

If you've stepped outside in recent days, you might have noticed the familiar sound of cicadas buzzing.

And while it's a soundtrack heard every summer, you wouldn't be wrong in thinking the insects have turned the decibels up further this year.

So why are cicadas so noisy this year?

Dr Michael Elias, an affiliate with CSIRO's Australian National Insect Collection, said it just came down to there beingmore cicadas this year.

"That's most likely because of the weather conditions we've been having for the last few years," he said.

"In most of eastern Australia, the ground's been pretty wet the last few years, which leads to increased plant growth."

During their juvenile stages, cicadas live underground and feed on sap from plant roots to survive.

"So with more plants being around, there's a lot more food available for them, so you get lower mortality in juveniles."

This year, Australia experienced its wettest January to August period since 2011 and monthly rainfall records have been shattered in parts of the country.

It's been the fifth consecutive year of above-average rainfall.

Why do they make so much noise?

It's part of their mating ritual.

Males of the same species tend to cluster together on tree trunks to form a communal mating display.

"The display is just the noise they're making … that's what the females are going to," Dr Elias explained.

"The reason they do that is because if you're not part of the group, if you're out there on your own, then any noise you make is going to be drowned out by the cicadas that are in the group.

"You have more competition because you're in a group of other males but you're better off being in there than out on your own, in a place where nobody's going to notice."

According to the Australian Museum, some species can produce a buzz in excess of 120 decibels.

That reach nears the limit of what the human ear can withstand and makes them the loudest insects in the world.

When will the cicadas stop making noise?

It will bea couple of months before you can expect a bit more quiet.

Dr Elias said whilesome species will finish up by the end of February,others will keep going until April.

Australia is estimated to have at least 1,000 species of cicadas but only about 250 are known to scientists.

While they can be found in almost every part of the country, most Australian species are found in the northern half of the continent.

"I would say early March, you're not going to get the very noisy cicadas anymore," Dr Elias said.

"By then, you'll notice a dramatic reduction in the amount of cicada noise."

That's becausethe insects only live as adults for a few weeks.

"But they don't all emerge at once," Dr Elias added.

"They're still emerging and they'll still keep emerging basically all of summer, or most of summer, anyway.

"It does depend a little bit on species, when they're going to emerge, what the conditions are."

Where do cicadas live?

As adults, you might have seen them (or their shells) peppering tree trunks.

But they spend most of their lives below our feet, living in burrows during their juvenile stage.

Common Australian species are estimated to spend up to seven years as nymphs before they come to the surface to mate.

Dr Elias said it was not known just how deep into the ground some get, though.

"Usually they're within the first half a metre of soil, below the surface, but they have been found up to two-and-a-half metres underground."