A firefly lights up at twilight. SUR
Iberian fireflies light up the night

Iberian fireflies light up the night

In Spain, you can still see these little 'flying fairies' in the countryside, but light pollution is dimming their brightness

José Antonio Guerrero


Friday, 1 September 2023

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The light of a firefly is so captivating that it can turn a nighttime stroll through the countryside into an incredibly magical moment. In the past, more fireflies were seen "because when we were little, we used to spend more time in the countryside and there were also more gardens near our homes," points out José Ramón Guzmán, a 53-year-old forest engineer and naturalist from Granada. He shares his love for these charming bioluminescent creatures on the website 'Gusanos de Luz' (Worms of Light), which he launched in 2009 alongside Belgian Raphaël de Cock. The website has now become a fantastic source of information about Iberian and Mediterranean fireflies.

The season to see fireflies is coming to an end although it is still possible to see some of these creatures in the northern part of the Iberian Peninsula. "The latest sightings we've received have come from the north, from Cantabria to Soria," explains Guzmán, after checking the most recent emails from the hundreds of individuals who send them photos and locations of fireflies.

They currently have around four thousand records of sightings in natural spaces, rural environments, urban parks and gardens throughout Spain. And he observes that the enchantment continues to grow. "There's a lot of interest in fireflies and I'm convinced that everyone would like to see one," he says.

That kind of LED-like glow in the midst of the night among the vegetation is the female firefly's brilliant strategy to attract the attention of males. The glowing signal turns off as soon as they mate.

Fireflies are always found near damp areas, irrigated land, riverbanks... but in recent years, light pollution and buildings have threatened to eclipse their glow. "There's much more artificial lighting now than there was 30 or 40 years ago. Excessive luminance affects fireflies; it blinds the males, and they're unable to locate the females.

The females, if surrounded by light, don't activate because they respond only to the absence of light. That's why they light up with the sunset," explains the naturalist. "They're not endangered," notes Guzmán, but this doesn't mean we shouldn't take care of them. "There are still many places to see them!"

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