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Glow-worms: glowing insects under threat because of light pollution from street lights

glow-worm.Image source, Getty Images
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Despite their name, glow-worms are actually a type of beetle

Scientists think glow-worm populations are falling due to light pollution from street lights.

The small critters are actually a type of beetle, and use the glowing light on their bottoms to attract others.

Zoologists have found artificial white light, like the glare from street lights, is having a devastating affect on glow-worms.

They're declining and disappearing in the UK and around the world as they struggle to find each other, mate and create new baby glow-worms.

What are glow-worms?

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Glow-worms are sometimes known as fireflies!

Glow-worms are small beetles usually found living under rocks. They can be found in grasslands, woodlands and even your garden too!

They're nocturnal - which means they stay up through the night. Male glow-worms look like typical beetles, but the females look more like larvae and emit a bright green light at night.

The female glow-worms climb up plant stems and glow. This gets the attention of the male glow-worms, who's eyes are attracted to their green glowing light.

Some studies have claimed that glow-worms are disappearing from our landscape.

— Professor Niven, Professor of Zoology, University of Sussex

But experts think that glow-worm numbers are falling.

Why are street lights affecting them?

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Image caption,

Only female glow worms are able to give off light

Glow-worms rely on their glowing light to attract each other to mate. But street lights and light pollution caused by non-natural light makes the glow from the creatures weaker and less visible to each other.

Light pollution has emerged as a key threat to insect populations alongside climate heating and land-use change.

— Professor Niven, Professor of Zoology, University of Sussex

Researchers conducted a test using a maze in a lab to see how much artificial light gets in the way of male glow-worms finding their female friends. In darkness, 70% are drawn to the green light of a female glow-worm.

When the "street lights" were turned on, only 21% found their way to the glowing light. The male glow-worms were confused by the bright white light and used a shield on their head to protect their eyes, like sunglasses.

We don't know exactly what the shield does but we think it acts like sunglasses to reduce the glare of bright light.

— Professor Niven, Professor of Zoology, University of Sussex

Researchers are hoping their work will help them to understand how to protect the glow-worm species, without needing to turn off all the lights.