Guest blog post by Paolo Mazzei
For decades, butterfly enthusiasts and lepidopterists across Italy have wondered: could the lost southern populations of the Southern Swallowtail still be out there?
Historical records of Papilio alexanor in Southern Italy were sparse and dated, often dismissed as stray individuals blown in by strong winds from Greece or the Balkans. But for many lepidopterists, alexanor represents a true holy grail – a majestic, bright-yellow species that is strictly protected.
Our research didn’t start in a lab, but with a smartphone screen.
When Citizen Science Meets Expert Curiosity
In May 2023, a marine biologist kayaking along the rugged cliffs of Basilicata uploaded a brief video to iNaturalist. It captured an unmistakable female Papilio alexanor fluttering around a giant fennel (Ferula) stalk.
A year later, a second record appeared on iNaturalist: a pristine, freshly emerged female photographed by a German tourist in Campania. Together, these two sightings hinted that the species might be more than a mere vagrant here.
This is where the power of modern biodiversity platforms like iNaturalist, Observation.org, and the eBMS (European Butterfly Monitoring Scheme) shines: they act as distributed networks of eyes on the ground, catching subtle shifts in nature that a single research team could easily miss. Inspired by these community sightings, our team from the Italian Lepidopterological Association (ALI), in collaboration with the University of Turin, decided it was time to step in.
A 1,400 km Journey into the Wild
Obtaining research permits for a strictly protected species under EU law takes time, ethics, and rigor. With support from the University of Turin, we secured formal authorization from the Italian Ministry of Environment in early 2026.
Driven by passion, our team funded the expedition ourselves, driving over 1,400 km round trip to systematically survey the steep coastal cliffs and dry habitats along the Campania–Basilicata border.
Pupa of Papilio alexanor. Photo by Paolo Mazzei. 
5th instar Papilio alexanor caterpillar. Picture by Stefano Meraglia, 
Papilio alexanor caterpillars feeding F. glauca. Picture by Paolo Mazzei. 
Papilio alexanor caterpillars of different instars, feeding on seeds of F. glauca. Picture by Stefano Meraglia. 
Papilio alexanor on C. ruber. Picture by Andrea Baruzzi,
The thrill of discovery was immediate. Standing at a cliffside turnout, we watched the first bright-yellow male soar up from the ravine. Soon we spotted courting pairs feeding on red valerian (Centranthus ruber) and females in the act of ovipositing.
Encouraged, we started scouting similar spots nearby, and the hunch paid off. About 15 to 20 km away, we found a second active breeding colony.
Surprising Ecology: A New Host Plant for Italy
Our fieldwork revealed two ecological twists, since published in our paper in Nota Lepidopterologica.
First, the Northern Italian populations rely on host plants such as Ptychotis saxifraga or Opopanax chironium, but the southern caterpillars feed exclusively on Ferula glauca. This host-plant association was previously documented in Greece and the Balkans, but never before in Italy.
Second, the flight begins significantly earlier here than in northern populations, reflecting local adaptation to the semi-arid, thermo-Mediterranean climate.
Protecting the Future: Simple Actions for Big Impact
Finding a “lost” population is cause for celebration, but it also brings responsibility. These isolated coastal colonies remain vulnerable to habitat fragmentation, fire, climate extremes, and road infrastructure development.
To help Papilio alexanor keep thriving here, effective conservation management should prioritise targeted monitoring, integrating structured transects through schemes like eBMS to track population trends over time; habitat protection, preserving coastal slope vegetation and preventing over-mowing or destruction of Ferula glauca stands during roadside maintenance; and responsible citizen engagement, encouraging nature lovers, hikers, and photographers to submit observations with precise geolocation, while ensuring that delicate breeding sites remain respected and undisturbed.
This story is a reminder that remarkable biological discoveries are still waiting to be made right under our noses. All it takes is a curious eye, a smartphone upload, and a community of passionate researchers ready to follow the trail.
Original source:
Meraglia S, Baruzzi A, Mazzei P, Valeri L, Zerunian Z (2026) First documented record of a reproducing population of Papilio alexanor Esper, 1800 (Lepidoptera, Papilionidae) in Southern Italy, with ecological notes. Nota Lepidopterologica 49: 157-170. https://doi.org/10.3897/nl.49.206084