Euchloe ausonides
In 3 days ~10% in a week ~20%
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 |
Rare
Under 5% of wildlife watchers report a Large Marble sighting in San Francisco on a given day, based on 55 verified sightings from GBIF citizen-science data. It is the 222nd most-seen of the 737 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
Any time of year
In every month with enough records, under 5% of wildlife watchers report a Large Marble in San Francisco on a given day, so our monthly data shows no clear season.
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.
Only San Francisco, in our data
San Francisco is the only city on Wallace's Line with enough records to rate Large Marble sightings: under 5% of wildlife watchers there report one on a given day.
GBIF citizen-science records
It is estimated from how often the Large Marble is recorded against all the insects logged in San Francisco (55 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.
