Leptotes cassius
In 3 days ~40% in a week ~70%
Leptotes cassius, the Cassius blue or tropical striped blue, is a butterfly of the family Lycaenidae. It is found in North America in Florida including the Keys, Texas south through the Caribbean, Mexico, and Central America to South America. Strays have been found in New Mexico, Kansas, Missouri, South Carolina, North Carolina and Virginia.
The wingspan is 20–35 mm. The butterfly species has an important role in Marisha Pessl's 2006 novel Special Topics in Calamity Physics. The protagonist, Blue van Meer, is named in honor of the Cassius blue. The caterpillars feed natively on Fabaceae. Food plants on record are Amorpha crenulata, woolly rattlepod (Crotalaria incana), Galactia regularis and lima bean (Phaseolus lunatus). It can also successfully develop feeding on Cape leadwort (Plumbago auriculata) or doctorbush (P. scandens), which (among the eudicots) are not closely related to its usual food plants. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Blue and John Crow Mountains National Park | 🇯🇲 Jamaica | |
| 2 | Everglades National Park | 🇺🇸 United States | |
| 3 | Iguazú National Park | 🇦🇷 Argentina | |
| 4 | Big Cypress National Preserve | 🇺🇸 United States | |
| 5 | Ría Lagartos Biosphere Reserve | 🇲🇽 Mexico | |
| 6 | Iguaçu National Park | 🇧🇷 Brazil | |
| 7 | Merritt Island National Wildlife Refuge | 🇺🇸 United States | |
| 8 | Cumbres de Monterrey National Park | 🇲🇽 Mexico |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Mendoza | 🇦🇷 Argentina | |
| 2 | Porto Alegre | 🇧🇷 Brazil | |
| 3 | São Paulo | 🇧🇷 Brazil | |
| 4 | Buenos Aires | 🇦🇷 Argentina | |
| 5 | Curitiba | 🇧🇷 Brazil | |
| 6 | Rosario | 🇦🇷 Argentina | |
| 7 | Caracas | 🇻🇪 Venezuela | |
| 8 | Miami | 🇺🇸 United States | |
| 9 | Cordoba | 🇦🇷 Argentina | |
| 10 | Vitória | 🇧🇷 Brazil |
Possible
About 20% of wildlife watchers report a Cassius Blue sighting in Buenos Aires on a given day, based on 417 verified sightings from GBIF citizen-science data. It is the 16th most-seen of the 558 insects we can rate there. Over three days the chance rises to about 40%, and over a week to about 70%, if each day is a fresh chance.
March to May
In those months about 30% of wildlife watchers report a Cassius Blue in Buenos Aires on a given day, against under 5% in July to December, the lowest months.
Between 10 am and 1 pm
Across all the parks we cover, that three-hour window holds the most Cassius Blue sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
Among the best
Of the 22 cities where we can rate Cassius Blue sightings, Buenos Aires ranks 4th at about 20%, level with the leaders once rounded. The best odds are in Mendoza (Argentina, about 20%), Porto Alegre (Brazil, about 20%) and São Paulo (Brazil, about 20%).
Same family: Lycaenidae
The closest relatives of the Cassius Blue that you can see in Buenos Aires (family Lycaenidae, Gossamer-winged Butterflies) are Strymon eurytulus (about 10%), Emesis russula (about 10%) and Lantana Scrub-Hairstreak (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Cassius Blue is recorded against all the insects logged in Buenos Aires (417 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.
