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An enigmatic new species of wormlion fly, whose larvae construct clever pitfall traps to capture prey, has been revealed in a study led by researchers at Dali University in China.

The fly, described in a recent paper in the open-access journal ZooKeys, was identified after a 2025 expedition successfully collected adult specimens in Yadong County, southern Xizang. Unidentified larvae belonging to the same group had first been collected in the region forty-eight years earlier in 1978, but because the adult stage remained unknown, scientists had been unable to confirm its true identity until now.

Analysing the physical traits of the newly discovered insect, the research team noted that it is particularly large for its group, with adult bodies measuring up to 19.5 millimetres in length and wings reaching nearly 16 millimetres long. The fully grown larvae are even larger, reaching lengths between 20 and 28 millimetres, and they possess a single semicircular proleg bearing a distinct row of five to seven spines.

It has been named Vermitigris tsangyanggyatso, with the species name dedicated to Tsangyang Gyatso, the sixth Dalai Lama, who was a celebrated seventeenth-century Tibetan poet-monk from Xizang known for his romantic verse and unconventional life.

The discovery increases the number of species recorded in China within the genus Vermitigris from one to two, expands the total number of species in the genus from four to five, and brings the total number of known living wormlion fly species in the world to sixty-seven.

The insect belongs to the brachyceran family Vermileonidae, a unique group of flies commonly known as wormlions. These flies are notable because their larvae employ a pitfall-feeding strategy that is evolutionarily convergent with pitfall-building antlions, making them the only known family of flies whose larvae capture prey by constructing funnel-shaped pits in loose sand or soil.

The team’s motivation to study this unique family stems from an unexpected discovery a decade ago:

“Well, it was probably an accidental discovery that first motivated us. In 2015, while searching for pit-building antlions on Cangshan Mountain in Dali, China, we discovered an unfamiliar larva that we found particularly interesting. However, because the adults have an extremely short lifespan, we failed for many years to determine its identity.

It was not until 2024 that we finally obtained adults through artificial rearing in the laboratory. It turned out to be a new species, which we named Vermiophis cangshanensis. This first discovery therefore took nine years. Since then, we have paid close attention to wormlions wherever we encounter them.”

Unlike some related lineages that diversified during the Late Mesozoic by developing elongated mouthparts to feed on nectar, this new species features a significantly shortened rostrum, suggesting that the adults do not feed at all during their final stage of life. Although adult flies were primarily found resting quietly on leaf surfaces near their larval breeding grounds on sunny days, one specimen was discovered further away around agricultural fields, indicating that the species possesses strong flight and dispersal capabilities.

The environment where the immature stages thrive consists of rain-protected microhabitats, which provide the stable microenvironments necessary for the wormlions to build their pitfall traps. The research team found the larvae living in three distinct types of sheltered habitats, including fine-grained soil under giant rocks, wood debris beneath a pavilion, and fine-grained river sands accumulated beside a river, with field observations indicating a strong preference for the river sands.

When asked about the specific physical features enabling the larvae to build effective traps across such diverse textures, the team noted:

“We honestly do not know yet. Perhaps future behavioural experiments will help answer this question.”

While wet forested regions have traditionally been shown to act as barriers to the dispersal of wormlion flies, this discovery highlights how the genus Vermitigris manages to thrive in such environments by exploiting these rain-protected microhabitats. The presence of this species on the southern slopes of the Himalayas suggests that the region serves as both a transitional zone and a biodiversity corridor, facilitating the penetration of Oriental elements into Eurasia.

The team elaborated on what this Himalayan discovery implies for the group’s evolutionary history:

“The previously known species were first discovered in tropical Southeast Asia, and these insects were therefore thought to be restricted to tropical regions. The discovery of this species suggests that they may also be capable of adapting to subtropical climates.

We hope that more unknown species will eventually be discovered in mainland Southeast Asia, such as Thailand, as well as in southwestern China, including Yunnan, Guizhou, and Sichuan Provinces.”

Vermitigris tsangyanggyatso is physically distinct from its closest relatives due to its uniform yellowish-brown to reddish-brown abdomen, which lacks the light and dark rings or longitudinal stripes seen on other species within the genus. Scientists believe that many neighbouring regions along the southern slopes of the Himalayas remain unsampled, meaning that further fieldwork could well yield additional members of this poorly documented group of flies.

Reflecting on the deeper personal connection to this work from a science communication standpoint, co-author Ji-Shen Wang shared:

“I would say that although my primary research interest is the insect order Mecoptera (scorpionflies), I have gradually expanded my interests into Diptera (flies) as well.

As a naturalist, I find the diversity of life on Earth endlessly fascinating, and this curiosity about nature continually motivates me to explore and wonder. I would like to quote Herman Melville from Moby-Dick: ‘As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas, and land on barbarous coasts.’”

Original study:

Shan L-X, Wang J-S (2026) After forty-eight years: An enigmatic new wormlion fly from Xizang, China (Diptera, Vermileonidae). ZooKeys 1276: 249-262. https://doi.org/10.3897/zookeys.1276.184675

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