Horisme tersata
In 3 days ~20% in a week ~40%
Horisme tersata, commonly known as the fern moth or simply the fern, is a moth of the family Geometridae. The species was first described by Michael Denis and Ignaz Schiffermüller in 1775 and it can be found in the Palearctic realm.
The wingspan is 31–36 mm. The length of the forewings is 14–18 mm. The moths fly in one or two generations from May to August.[1] The larvae feed on Clematis vitalba. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cévennes National Park | 🇫🇷 France |
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | London | 🇬🇧 United Kingdom |
With luck
About 10% of wildlife watchers report a Fern Moth sighting in Cévennes National Park on a given day, based on 27 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 345th most-seen of the 996 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
April–June and September
In those months about 10% of wildlife watchers report a Fern Moth in Cévennes National Park on a given day, against under 5% in July–August and October–March, the lowest months.
Between 6 and 9 am
Across all the parks we cover, that three-hour window holds the most Fern Moth sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Only Cévennes National Park, in our data
Cévennes National Park is the only park on Wallace's Line with enough records to rate Fern Moth sightings: about 10% of wildlife watchers there report one on a given day.
GBIF citizen-science records
It is estimated from how often the Fern Moth is recorded against all the insects logged in Cévennes National Park (27 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
