Euchloe ausonides
In 3 days ~30% in a week ~50%
Euchloe ausonides, the large marble or creamy marblewing, is a species of butterfly that occurs in western North America. It lays eggs on the terminal flower buds of a variety of plants in the mustard family, including introduced Eurasian species, and the larvae feed on the buds, flowers and fruit of these plants. In California, it has witnessed population declines since the 1980s, especially in the Central Valley and the Bay Area. In Washington, subspecies the island marble butterfly (Euchloe ausonides ssp. insulanus) was listed as an endangered species under the Endangered Species Act in 2020.
The caterpillar is a dark green to a bluish gray color that is covered in black dots. It is marked with yellow and white stripes lengthwise along its back and sides. The size of the caterpillar reaches a length of 3/4 in.
The large marble is a medium-sized butterfly. It has white scales that are scattered in the forewing and a black pattern on the tip of the forewing. There is compact green marbling on the underside of the hindwing. The wingspan of this butterfly can go from 3.8 - 5.1 cm.
Females of E. ausonides are able to move at greater distances and speeds than males.... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Isle Royale National Park | 🇺🇸 United States | |
| 2 | Rocky Mountain National Park | 🇺🇸 United States | |
| 3 | Grand Teton National Park | 🇺🇸 United States | |
| 4 | Yellowstone National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | San Francisco | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Large Marble sighting in Rocky Mountain National Park on a given day, based on 33 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 38th most-seen of the 191 insects we can rate there. Over three days the chance rises to about 30%, and over a week to about 50%, if each day is a fresh chance.
June
In that month about 20% of wildlife watchers report a Large Marble in Rocky Mountain National Park on a given day, against under 5% in August to April, the lowest months.
Between noon and 3 pm
Across all the parks we cover, that three-hour window holds the most Large Marble sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
2nd of 4
Of the 4 parks where we can rate Large Marble sightings, Rocky Mountain National Park ranks 2nd at about 10%. The best odds are in Isle Royale National Park (United States, about 20%).
Same family: Pieridae
The closest relatives of the Large Marble that you can see in Rocky Mountain National Park (family Pieridae, Whites, Yellows, and Sulphurs) are Mead's Sulphur (about 10%), Margined White (about 10%) and Queen Alexandra’s Sulphur (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Large Marble is recorded against all the insects logged in Rocky Mountain National Park (33 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.
