Drasteria adumbrata
In 3 days ~20% in a week ~30%
Drasteria adumbrata, the shadowy arches, is a moth of the family Erebidae. The species was first described by Hans Hermann Behr in 1870. It is found from coast to coast in southern Canada, south in the west to California and Colorado, south in the east to New England and Michigan. Subspecies D. a. alleni is found from eastern Alberta to New York and Nova Scotia. Subspecies D. a. saxea occurs from southern British Columbia and south-west Alberta south to California and Colorado.
The wingspan is about 32 mm. Adults are on wing in summer. The larvae feed on Vaccinium angustifolium and probably other Vaccinium species. It has also been recorded on Arctostaphylos uva-ursi. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Glacier National Park | 🇺🇸 United States |
More parks will be added in future updates.
With luck
About 10% of wildlife watchers report a Shadowy Arches sighting in Glacier National Park on a given day, based on 6 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 119th most-seen of the 147 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 30%, if each day is a fresh chance.
June and July
In those months about 10% of wildlife watchers report a Shadowy Arches in Glacier National Park on a given day, against under 5% in August to May, the lowest months.
Between 4 and 7 pm
Across all the parks we cover, that three-hour window holds the most Shadowy Arches sightings with a recorded time, and about 7 in 10 of them come between 6 am and 6 pm: it is most active around dawn and dusk.
Only Glacier National Park, in our data
Glacier National Park is the only park on Wallace's Line with enough records to rate Shadowy Arches sightings: about 10% of wildlife watchers there report one on a given day.
Same family: Erebidae
The closest relatives of the Shadowy Arches that you can see in Glacier National Park (family Erebidae, Underwing, Tiger, Tussock, and Allied Moths) are Spotted Tussock Moth (about 30%), Police Car Moth (about 20%) and Virginian Tiger Moth (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Shadowy Arches is recorded against all the insects logged in Glacier National Park (6 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.
