Thetidia smaragdaria
In 3 days ~30% in a week ~60%
The Essex emerald (Thetidia smaragdaria) is a moth of the family Geometridae. The species was first described by Johan Christian Fabricius in 1787 as Phalaena smaragdaria. It is distributed throughout the Palearctic region with records from many European countries. The British subspecies Thetidia smaragdaria maritima was last seen in 1991 in Kent and is now presumed extinct. In 2004 the moth was first recorded from Sweden.
The wingspan is 27–35 mm. There is one generation per year with adults on wing from mid-June to mid-July. The larvae feed on Artemisia maritima and Achillea millefolium. Larvae can be found from July to June the following year. It overwinters in the larval stage. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Aigüestortes National Park | 🇪🇸 Spain | |
| 2 | Pyrénées National Park | 🇫🇷 France | |
| 3 | Sierra de Guadarrama National Park | 🇪🇸 Spain |
With luck
About 10% of wildlife watchers report an Essex Emerald sighting in Aigüestortes National Park on a given day, based on 9 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 190th most-seen of the 256 insects we can rate there. Over three days the chance rises to about 30%, and over a week to about 60%, if each day is a fresh chance.
July
In that month about 20% of wildlife watchers report an Essex Emerald in Aigüestortes National Park on a given day, against under 5% in September to June, the lowest months.
Between 4 and 7 am
Across all the parks we cover, that three-hour window holds the most Essex Emerald sightings with a recorded time, and about 7 in 10 of them come between 6 pm and 6 am: it is most active around dawn and dusk.
Yes
Of the 3 parks where we can rate Essex Emerald sightings, Aigüestortes National Park has the highest daily chance: about 10%. Next come Pyrénées National Park (France, under 5%) and Sierra de Guadarrama National Park (Spain, under 5%).
Same family: Geometridae
The closest relatives of the Essex Emerald that you can see in Aigüestortes National Park (family Geometridae, Geometer Moths) are Shaded Broad-Bar (about 20%), Psodos quadrifaria (about 20%) and Latticed Heath (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Essex Emerald is recorded against all the insects logged in Aigüestortes National Park (9 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.
