Echinargus isola
In 3 days ~70% in a week ~90%
Echinargus isola, or Reakirt's blue, is a butterfly of the family Lycaenidae. It is the sole representative of the monotypic genus Echinargus. It is found in Central America and the extreme southern U.S. Echinargus isola migrates regularly throughout most of the U.S. almost to the Canada–United States border, and very rarely into the southern prairies.
The wingspan is 16–23 mm. Adults are on wing from June to October in the north and year-round in south. Its habitats include fields, gardens, open areas, and host plants. The larvae feed on Fabaceae, particularly mesquites (Prosopis species). Adults feed on flower nectar from spearmint, white sweet clover, and a variety of other herbs. 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 | Guadalupe Mountains National Park | 🇺🇸 United States | |
| 5 | Grand Canyon National Park | 🇺🇸 United States | |
| 6 | Padre Island National Seashore | 🇺🇸 United States | |
| 7 | Cumbres de Monterrey National Park | 🇲🇽 Mexico | |
| 8 | Death Valley National Park | 🇺🇸 United States | |
| 9 | Joshua Tree National Park | 🇺🇸 United States | |
| 10 | Rocky Mountain National Park | 🇺🇸 United States | |
| 11 | Zion National Park | 🇺🇸 United States | |
| 12 | Yosemite National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | San Antonio | 🇺🇸 United States | |
| 2 | Puebla | 🇲🇽 México | |
| 3 | Austin | 🇺🇸 United States | |
| 4 | Monterrey | 🇲🇽 México | |
| 5 | Denver | 🇺🇸 United States | |
| 6 | Guadalajara | 🇲🇽 México | |
| 7 | Mexico City | 🇲🇽 México | |
| 8 | San Luis Potosí | 🇲🇽 México | |
| 9 | Dallas | 🇺🇸 United States | |
| 10 | Torreón | 🇲🇽 México |
Possible
About 30% of wildlife watchers report a Reakirt's Blue sighting in Big Bend National Park on a given day, based on 188 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 3rd most-seen of the 329 insects we can rate there. Over three days the chance rises to about 70%, and over a week to about 90%, if each day is a fresh chance.
May–June, August and December
In those months about 40% of wildlife watchers report a Reakirt's Blue in Big Bend National Park on a given day, against about 20% in January to March, the lowest months.
Between 11 am and 2 pm
Across all the parks we cover, that three-hour window holds the most Reakirt's Blue 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 12 parks where we can rate Reakirt's Blue sightings, Big Bend National Park has the highest daily chance: about 30%. Next come Saguaro National Park (United States, about 20%) and Bahía de Loreto National Park (Mexico, about 20%).
Same family: Lycaenidae
The closest relatives of the Reakirt's Blue that you can see in Big Bend National Park (family Lycaenidae, Gossamer-winged Butterflies) are Gray Hairstreak (about 30%), Marine Blue (about 30%) and Western Pygmy-Blue (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Reakirt's Blue is recorded against all the insects logged in Big Bend National Park (188 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.
