Gem Moth

Gem Moth

Orthonama obstipata

Daily sighting probability <5% · Rare
at San Francisco

In 3 days ~10%

11 Verified sightings at San Francisco
8 In 1 park From 2019 to 2026
November Best month
🌙 Nocturnal When it's spotted

About the Gem Moth

Orthonama obstipata, the gem, is a moth of the family Geometridae. The species was first described by Johan Christian Fabricius in 1794. It is a cosmopolitan species. In continental Europe though in the northeast, its range does not significantly extend beyond the Baltic region and it is absent from northern Russia. This well-flying species is prone to vagrancy and able to cross considerable distances of the open sea; it can thus be regularly found on the British Isles (though mainly in the south) and even on Iceland.

Under its junior synonyms Nycterosea brunneipennis and Geometra fluviata, the gem is the type species of genera Nycterosea and Percnoptilota, respectively. The latter is treated as a junior synonym of the former, but Nycterosea, though usually included in Orthonama these days, may warrant recognition as an independent genus after all.

The adult's wingspan is 18–21 mm (0.71–0.83 in); in their core range (e.g. Belgium and the Netherlands) they can be seen between April and November, but in outlying regions, they may only be regularly encountered in late summer and early autumn, when vagrant individuals abound. This species is strongly sexually... Wikipedia →

Global Distribution

Parks Where Found

# Park Country Daily sighting probability
1 Shenandoah National Park 🇺🇸 United States
~10%

More parks will be added in future updates.

Cities Where Found

# City Country Daily sighting probability
1 Porto 🇵🇹 Portugal
~10%
2 Austin 🇺🇸 United States
~10%
3 Baltimore 🇺🇸 United States
~10%
4 Dallas 🇺🇸 United States
~10%
5 Chicago 🇺🇸 United States
~10%
6 Detroit 🇺🇸 United States
<5%
7 Washington 🇺🇸 United States
<5%
8 Toronto 🇨🇦 Canada
<5%
9 Madrid 🇪🇸 Spain
<5%
10 Philadelphia 🇺🇸 United States
<5%

Before you go

What are the chances of seeing a Gem Moth in San Francisco?

Rare

Under 5% of wildlife watchers report a Gem Moth sighting in San Francisco on a given day, based on 11 verified sightings from GBIF citizen-science data. It is the 458th most-seen of the 737 insects we can rate there. Over three days the chance rises to about 10%, if each day is a fresh chance.

When is the best time to see a Gem Moth in San Francisco?

Any time of year

In every month with enough records, under 5% of wildlife watchers report a Gem Moth in San Francisco on a given day, so our monthly data shows no clear season.

What time of day is best to see a Gem Moth?

Between 9 pm and midnight

Across all the parks we cover, that three-hour window holds the most Gem Moth sightings with a recorded time, and about 8 in 10 of them come between 6 pm and 6 am: it is mostly seen at night.

Is San Francisco the best place to see a Gem Moth?

25th of 25

Of the 25 cities where we can rate Gem Moth sightings, San Francisco ranks 25th at under 5%. The best odds are in Porto (Portugal, about 10%), Austin (United States, about 10%) and Baltimore (United States, about 10%).

Where does the Gem Moth sighting chance come from?

GBIF citizen-science records

It is estimated from how often the Gem Moth is recorded against all the insects logged in San Francisco (11 verified sightings), 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.

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