South Africa: Moth thought extinct rediscovered after 147 years

Until a few years ago, the geometrid moth Drepanogynis insciata, which for a long time was listed under the name Axiodes insciata, was little more than a footnote in entomology. For nearly 150 years, only two historical museum specimens from the vicinity of the South African town of Swellendam and old illustrations existed of this strikingly beautiful, emerald-green moth. The heavily faded specimens are still kept today at the Natural History Museum in London.

Only photos on the citizen-science platform iNaturalist changed this picture fundamentally: between 2020 and 2023, nature observers documented 13 sightings of male specimens at four sites in South Africa’s Western Cape. These were the first confirmed live records of the species since the 19th century.

Historical traces

The scientific original description of Drepanogynis insciata was published in 1875 by the Austrian entomologists Cajetan and Rudolf Felder as well as Alois F. Rogenhofer, based on a male holotype specimen from South Africa. There is much to suggest that this individual was already collected in 1857 during the Novara Expedition, the first circumnavigation of the Austrian Navy.

A second male specimen, preserved without precise date or locality information, likely comes from the collection of the French entomologist Jean-Baptiste Boisduval and was collected before 1879. His collection was transferred to the Natural History Museum in London in 1927.

Contemporary illustrations suggest that the moth was originally an intense emerald green in color. Over the decades, the two historical museum specimens lost their coloration and today appear brownish to salmon-colored.

Its scientific classification also proved difficult for a long time. In its original description, the species was initially assigned to a different genus and was later listed under the name Axiodes insciata. In the decades that followed, its systematic placement changed several times, as experts disagreed about how best to classify related geometrid species.

Only a comprehensive revision in 2002 ultimately assigned the species to the genus Drepanogynis , and several previously separate genera—including Axiodes—were merged. The reassessment was based primarily on shared morphological traits such as the green wing coloration and characteristic structures of the male genitalia.

To this day, Drepanogynis insciata is regarded as the officially accepted name, even though the exact delimitation of the genus remains the subject of scientific debate.

2020: One photo changes everything

The first modern photo of Drepanogynis insciata was taken by Cameron Scott, who photographed the moth in September 2020 at the Gondwana Private Game Reserve, about 160 kilometers west of Swellendam. South African lepidopterist Hermann S. Staude immediately recognized the importance of the image: the lost species was still alive.

At Staude’s request, Scott captured an individual in January 2022 as a voucher specimen for scientific investigation. It was then analyzed by Staude and his colleague Pasi Sihvonen of the Finnish Museum of Natural History in Helsinki and formed the basis for the reassessment of the species.

What did the reassessment of the rediscovered moth reveal?

For the study published in ZooKeys in December 2025, Drepanogynis insciata was examined for the first time using modern methods, including DNA analyses and high-resolution micro-CT scans.

Genetic material was obtained from a leg of the specimen collected in 2022. The genetic analysis showed that the species has a distinct profile—meaning it is not a variant of another moth, but biologically clearly distinct. Its closest relative is Drepanogynis smaragdaria, but the two differ genetically by almost 6%, a substantial distance in the insect world.

In addition, the species was documented in detail morphologically for the first time. Using X-ray 3D imaging, even the finest wing structures could be made visible. This showed that the wing veins are unusually fused, the wing margins are strongly jagged, and the internal structures are characteristically arranged—key traits for distinguishing it from similar species.

The male genitalia also proved particularly informative. As in many moths, they are species-specific. In D. insciata, a unique combination of hooks, plates, and fine tooth-like structures can be seen, enabling unambiguous identification.

Based on several genes, the researchers also created a comprehensive phylogenetic tree with more than 1,200 geometrid species. This allowed D. insciata to be clearly assigned to the subfamily Ennominae and the tribe Drepanogynini.

Range: limited to a few refuges

The reassessment showed just how extremely limited the occurrence of the geometrid moth Drepanogynis insciata is. All confirmed records come from only five isolated sites in South Africa’s Western Cape, within a radius of around 150 kilometers around Swellendam.

All localities lie within the Fynbos biome, a globally unique belt of vegetation at the southwestern tip of Africa. This species-rich ecosystem stretches along the coasts and mountain ranges of the Western and Southern Cape and is known for its exceptional diversity of shrubs, heaths, and flowering plants.

Within this biome, D. insciata appears to be linked mainly to the rare Renosterveld —a vegetation type associated with the Fynbos—as well as adjacent coastal landscapes at elevations below 330 meters.

These habitats, in particular, are now among the most heavily degraded landscapes in South Africa. They have been intensively used for agriculture for centuries, especially as wheat fields and grazing land. Added to this are urbanization, invasive plants, and recurring fires. As a result, only about 5% of the original Renosterveld remains. These few remaining fragments likely form the last refuges of this geometrid species.

Due to the limited data available, the researchers classified Drepanogynis insciata under IUCN guidelines as Data Deficient (DD).

Short observation window

Its occurrence is also strongly limited in time. All known observations come from the months of September to January. In this short phase, the adult moths appear to be active, possibly in two generations per year.

Notably, all specimens were found at night at artificial lights. During the day, the species apparently remains hidden. Without targeted nocturnal observations—such as light-trap monitoring or chance finds at illuminated buildings—it likely would have remained undiscovered.

The great unknown: the caterpillars of Drepanogynis insciata

Despite the rediscovery and intensive research, much about Drepanogynis insciata remains unknown. So far, only males have been documented. Females have never been observed —presumably because egg-carrying individuals are less active and are less likely to be attracted to light.

The species’ caterpillars have also not yet been scientifically described. Accordingly, it is unknown which plants they feed on. Possible host plants include grasses, herbs, or tree leaves; the larvae may even use multiple plant species.

According to a report by Mongabay, Hermann Staude is already searching specifically for caterpillars in suitable Fynbos areas by beating shrubs, collecting falling larvae, and rearing them. Only when a caterpillar develops into an adult moth can its identity be confirmed unequivocally.

The fact that no caterpillars have been found so far likely has several reasons:

• the very small population size,
• their excellent camouflage, since geometrid caterpillars often resemble twigs or leaf stalks,
• the unknown host plants,
• short development times of only a few weeks per year
• as well as the highly fragmented habitat, some of which is privately used.

This search for the caterpillars is enormously important for protecting the species. In butterflies and moths, the caterpillar is the decisive life stage: it feeds and grows, is tied to specific plants, and determines where a species can survive at all. As long as its host plants are unknown, it is difficult to determine which habitats must be preserved.

The researchers consider the biology of D. insciata to still be largely unexplored. They recommend systematic light-trap monitoring, targeted caterpillar searches, expanding genetic reference data, and—if possible—controlled rearing in human care.

A glimmer of hope – and a warning

The case of Drepanogynis insciata shows that species can survive for decades without being discovered—not because they are gone, but because nobody is looking for them in a targeted way. Other moths that were long considered lost, such as the moth Lignyoptera thaumastaria, have also only been confirmed again in recent years after already being considered lost.

At the same time, this rediscovery makes it clear that the ongoing loss of habitats remains the greatest threat to many organisms. Even species that still exist can slip unnoticed toward disappearance when their last refuges are destroyed.

The story of D. insciata also illustrates how much biological research has changed. Modern genetic methods and digital platforms such as iNaturalist now enable close collaboration between professional scientists and committed amateurs. Without this networking, the species would likely still be regarded as lost.

Other rediscoveries also show how central a role citizen science now plays. For example, the western red cicada (Okanagana arctostaphylae) and the chestnut casebearer moth (Coleophora leucochrysella) became known again in 2020 only through observations shared online. Without the many volunteer nature observers, numerous species would likely remain invisible—and thus unprotected.

But the study also points to a structural problem: worldwide there are too few taxonomists, especially for nocturnal insects. Many species are considered “lost” simply because they were never systematically searched for again.

The story of Drepanogynis insciata thus stands in for many unknown and overlooked species. It is a glimmer of hope because it shows that life can persist even under difficult conditions—and a warning to look more closely before overlooked species truly become lost ones.

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Sources

• Sihvonen, P., Lee, K. M., Söderholm, M., et al. (2025). Drepanogynis insciata (Felder & Rogenhofer, 1875), a South African geometrid moth lost to science rediscovered after more than 140 years (Lepidoptera, Geometridae, Ennominae). ZooKeys, 1261, 261–276. https://doi.org/10.3897/zookeys.1261.171904
• Truscott, R. (2026, February 11). Citizen science rediscovers rare South African moth. Mongabay.
  https://news.mongabay.com/2026/02/citizen-science-rediscovers-rare-south-african-moth/