Fireflies Galore: Where and When to See These Amazing Bugs in Trieste

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by Alessandra Ressa

Love is in the air, and the fireflies sure know all about it! The end of June and the beginning of July marks the mating season for these truly amazing creatures, whose survival depends entirely on how successful they are at finding a partner to reproduce with in a little over three weeks. To achieve this, they need special environmental conditions, which are becoming scarcer due to urbanization. To live and mate, fireflies need dark, humid places, mild temperatures, greenery, and clean air.

In Trieste, there used to be many areas where people enjoyed the plentiful night glows of these tiny bugs, especially in the suburbs where streams crossed damp green areas and flowed into the city, such as San Giovanni and Cattinara. Every year at dusk, families sat in the cool outdoors of early summer evenings to marvel at the ancestral and magical dance of fireflies. Today, it is almost impossible to spot fireflies anywhere in Trieste. Air pollution, deforestation, artificial lights, chemicals on plants, and the almost total disappearance of the city streams, now buried under roads, have caused their near-total disappearance.

Do not despair, however. There are still some spots in town where you can see fireflies in abundance until the mating season is over. One very popular place is along the bike lane Cottur near the village of San Giuseppe della Chiusa. For some reason, thousands of fireflies continue to meet there year after year, notwithstanding the huge crowds of loud Triestini trying to catch them on camera or video, pointing flashlights, and letting their obnoxious children catch them, often smashing them in their tiny, sweaty hands. Now that I have warned you not to plan a romantic date there, I should add that this is the best place to see fireflies in Trieste. If you can cope with rude humans, you will not be disappointed. If you are lucky and the evening is particularly promising, you can get away from the crowds, stroll along the bike lane, and find your own secluded spots.

Another place for spotting fireflies on particularly warm evenings is Longera, along the trail of the Rio Farnetello stream, at the foot of the Bosco del Farneto wood. This part of the stream has miraculously survived burial (though it soon disappears under cement once it reaches San Giovanni) and offers the right amount of dampness, darkness, and greenery for fireflies to enjoy. Here you won’t find many people (Triestini are creatures of habit and tend to go where everybody else goes), and you can stroll along the beautiful trail by the stream (which ends abruptly into someone’s private property) or dare to take one of the trails that climb Bosco del Farneto and lead all the way to central Viale XX Settembre. Bring a flashlight if you do.

There are approximately 2,000 firefly species in the world. In Trieste, the main species is called Luciola. During mating season, males fly gently around with their own unique flashing pattern (each species has its own), while females don’t fly. Instead, they wait on rocks, trees, or on the ground, sitting still in a mating position with their abdomen up, and signal their location with their own steady light to be easily spotted by the flying males. It’s a frantic rush for love. Male fireflies only live two weeks, so there’s no time for courtship—it’s straight to business. Interestingly, adult fireflies don’t eat either. Their energy at the adult stage comes from the many snails eaten as larvae. Firefly larvae are very fat, aggressive, and poisonous, and not as attractive as their parents.

Because of their short life span and the fact that for most of the year they keep low, hidden under earth or plants, it is hard for scientists to determine in what numbers they are truly disappearing.

As for their glow, fireflies have special organs under their abdomen that take in oxygen. Inside special cells, they combine the oxygen with a substance called luciferin to make light with almost no heat. They use this light, called bioluminescence, to light up the ends of their abdomen. Because each species has its own unique flashing pattern, when a male firefly wants to communicate with a female, he flies near the ground while flashing his light every few seconds. Once he is near the ground, a female can easily tell if he’s from the same species as she is, and if so, if she fancies him, she answers his flashes by turning on her light. Isn’t it amazing? You glow, guys!

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Alessandra Ressa
“Born to Italian-Scottish parents, an explosive combination, reason for my restlessness and love for good food, I’ve moved from San Francisco, California to Trieste 20 years ago. I have a degree in Mass Communication from the University of California, Berkeley, and a Master’s degree in International Cooperation from the Scuola Superiore di Studi Universitari in Pisa. In San Francisco I worked for several years as a journalist and press officer before moving to Albania, Bosnia, Kosovo and other war stricken countries with the United Nations. I am a professional journalist and English teacher, I love the outdoors, exploring caves and unusual places, travelling, meeting people, the opera, singing, the scent of the sea and the whistle of the wind. No other city in the world other than Trieste can offer all this.”


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