By Melissa Fleur Afshar
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A new species of ladybird beetle has been discovered by scientists—and it was living right on the researcher's doorstep, having been found on the campus of Japan's Kyushu University.
The tiny black ladbug, Parastethorus pinicola, was spotted on a pine tree at the university’s Hakozaki Satellite campus. For entomologist professor Munetoshi Maruyama of the Kyushu University Museum, who supervised the study, the find shows how much can still be uncovered by examining familiar environments more closely.
“These ‘minor’ insects support our ecosystems," Maruyama said in a statement. “People rarely notice such small insects. But as our study showed, even in a city or on a university campus, there are unknown species living right beside us."
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The discovery forms part of a three-year project to revise the classification of Stethorini, a tribe of minute ladybirds best known for feeding on spider mites.
The review is the first major update to Japan’s understanding of these insects in more than 50 years.
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Parastethorus pinicola—a name that means “pine dweller”—measures just over one millimeter in lenght. Although extremely small, the beetle stood out once the research team examined it under controlled study conditions.
Its presence on a tree growing on the university grounds shows how species can sometimes remain unnoticed even in well‑studied areas.
To resolve long-standing issues in the classification of Japan’s Stethorini, the research team examined approximately 1,700 specimens. Their review addressed historical confusion between several species and corrected one notable misidentification.
The beetle long known in Japan as Stethorus japonicus was determined to be the same species as Stethorus siphonulus, which is widely distributed across China and Southeast Asia. The clarification helps align Japan’s classification with regional records and gives researchers a clearer understanding of the group’s diversity.
Alongside the discovery of P. pinicola, the review also identified a second new species from Hokkaido. This beetle has been named Stethorus takakoae, adding another entry to Japan’s updated list of Stethorini species.
Together, these findings provide a clearer picture of the group’s presence across the country and highlight how taxonomic work can reveal overlooked biodiversity.
For the researchers, the discoveries serve as a reminder that important scientific updates are not always found in remote locations.
“Normally, insect collectors do not pay much attention to pine trees, which is perhaps why scientists have overlooked this species for so long," said Kyushu University entomologist Ryōta Seki in a statement.
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Reference
Seki, R., & Maruyama, M. (2025). Review of the genera Stethorus and Parastethorus from Japan (Coleoptera: Coccinellidae). Acta Entomologica Musei Nationalis Pragae, 65(2), 269–291. https://doi.org/10.37520/aemnp.2025.021
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