Eurema mexicana
In 3 days ~50% in a week ~80%
Eurema mexicana, the Mexican yellow, sometimes called the wolf-face sulphur, is a North and South American butterfly in the family Pieridae. It occurs mainly in Mexico but occasionally is found in central and southwestern United States and rarely in Canada.
The upperside of the wings is pale yellow with a black forewing submarginal border outlining a "dog" or "wolf-face" pattern. The hindwing has a small outer margin black border. The male has a bright yellow patch on the leading edge of the hindwing. The underside of the wings is pale yellow in summer individuals and pale yellow with reddish markings or all reddish pink in winter individuals. The hindwing is sharply pointed. The wingspan measures 1+1⁄4 to 2+1⁄4 inches (32–57 mm).
Similar species in the Mexican yellow's range include Boisduval's yellow (Eurema boisduvaliana) and the Salome yellow (Eurema salome). Boisduval's yellow is smaller and brighter yellow, the male has a weaker "dog face" pattern, the female has reduced black on the upper side, and the hindwing is less sharply pointed.
The Salome yellow is brighter yellow, has more limited black on the upperside, and the underside... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Big Bend National Park | 🇺🇸 United States | |
| 2 | Saguaro National Park | 🇺🇸 United States | |
| 3 | Bahía de Loreto National Park | 🇲🇽 Mexico | |
| 4 | Cumbres de Monterrey National Park | 🇲🇽 Mexico | |
| 5 | Joshua Tree National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | San Luis Potosí | 🇲🇽 México | |
| 2 | Monterrey | 🇲🇽 México | |
| 3 | Mexico City | 🇲🇽 México | |
| 4 | San Antonio | 🇺🇸 United States | |
| 5 | Phoenix | 🇺🇸 United States | |
| 6 | Dallas | 🇺🇸 United States |
Possible
About 20% of wildlife watchers report a Mexican Yellow sighting in Big Bend National Park on a given day, based on 82 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 19th most-seen of the 329 insects we can rate there. Over three days the chance rises to about 50%, and over a week to about 80%, if each day is a fresh chance.
November
In that month about 40% of wildlife watchers report a Mexican Yellow in Big Bend National Park on a given day, against about 10% in February and March, the lowest months. That is one of Big Bend National Park's driest months, with about 10 mm of rain against 50 mm in September.
Between noon and 3 pm
Across all the parks we cover, that three-hour window holds the most Mexican Yellow sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
Yes
Of the 5 parks where we can rate Mexican Yellow sightings, Big Bend National Park has the highest daily chance: about 20%. Next come Saguaro National Park (United States, about 10%) and Bahía de Loreto National Park (Mexico, about 10%).
GBIF citizen-science records
It is estimated from how often the Mexican Yellow is recorded against all the insects logged in Big Bend National Park (82 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.
