What do cicadas do for the environment? What purpose do they serve?

Bruno Cooke June 9, 2021

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Reports of cicadas causing car crashes, grounding a White House press charter flight, and being a presidential nuisance, have led Americans to wonder, what purpose do cicadas serve? Do they sleep? Are they blind? What do cicadas do for the environment, and what do they do underground for 17 years?

What do cicadas do for the environment?

Preventing an aircraft from flying at its scheduled departure time doesn’t constitute doing something for the environment, although one might interpret it as such.

But cicadas actually do a lot of good for regional ecology, according to National Geographic.

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Cicadas alight on a plant in Virginia, U.S. Photographer: Julia Schmalz/Bloomberg

While male cicadas die immediately after mating, females lay 500 eggs each in tree branches, which hatch two months later.

On falling to the ground, the “ant-like nymphs” burrow into the earth to evade predators and settle a foot below the surface.

This full process turns over soil, naturally prunes trees, boosts predator populations and returns nutrients to the earth via decomposition.

What other purpose do cicadas serve?

Besides what cicadas do for the environment, Kritsky entomologist Gene Kritsky reckons cicadas serve another purpose.

Their periodic reappearance, Kritsky suggests (in the Guardian), provides an opportunity to reflect on the passage of time.

“We don’t know when the pandemic will end,” he says, “but the cicadas came out in May.” This much we do know.

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What do cicadas do underground for 17 years?

When cicadas burrow into the soil, they settle for a while – it can be 13 years, or 17 years, or just about any other length of time, depending on the species.

They spend most of their life down there, but what do they get up to?

In their larval form, they latch on to a tree’s roots and feed on their host’s fluids.

Given the regularity and synchronicity of a brood’s generational cycle, one can predict closely when a new brood will emerge.

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Cicadas have bright red eyes

Do cicadas sleep?

During time spent underground, cicadas don’t spend the whole time sleeping or hibernating, as many people might think.

Instead, they drink the sap from tree roots, twigs and branches.

If and when they do “sleep” underground – between glugs of tree sap, say – they actually do the insect equivalent of sleeping, called “torpor”.

Are cicadas blind?

No, cicadas aren’t technically blind, although they might look like it when they fly straight into you.

Cicadas actually have five eyes – two bright red compound eyes and three simple eyes (or ocelli). 

Cicadas can in fact see. The larger compound eyes, which sit on either side of the head, “visually perceive the world around them”.

Meanwhile the smaller, simple eyes are only capable of perceiving the difference between light and dark. But having three of them in a triangle formulation may be more useful than simple light recognition might seem.

Reports of cicadas causing havoc have taken Twitter by storm

From Biden swatting a cicada off his neck before boarding Air Force One –

To the White House press charter experiencing mechanical issues…

Cicadas may be small, but there is strength in numbers. This year’s generation – Brood X – have certainly made themselves known.

Bruno is a postgraduate student studying global journalism, with research interests in the intersection of the media, storytelling, culture and politics. His articles have appeared in Groundviews, Packs Light and Forge Press, and most are readable on Medium or onurbicycle.com. He is a Student Ambassador for Tortoise Media, a big fan of Freddie Mercury and a novelist – his debut novel, Reveries, is available on Amazon.