Tarsocera cassina
In 3 days ~30% in a week ~50%
Tarsocera cassina, the sand-dune widow, is a butterfly of the family Nymphalidae. It is found in South Africa in the Western Cape along the coast from Lambert's Bay to Bredasdorp. The wingspan is 35–40 mm for males and 40–45 mm for females. Adults are on wing from September/October to November. There is one generation per year
The larvae feed on various Poaceae species, including Lolium species and Brachypodium distachyum. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | West Coast National Park | 🇿🇦 South Africa |
More parks will be added in future updates.
With luck
About 10% of wildlife watchers report a Sand-Dune Widow sighting in West Coast National Park on a given day, based on 5 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 32nd most-seen of the 44 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.
October
In that month about 30% of wildlife watchers report a Sand-Dune Widow in West Coast National Park on a given day, against under 5% in November to August, the lowest months. That is one of West Coast National Park's driest months, with about 15 mm of rain against 70 mm in June.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Sand-Dune Widow sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
Only West Coast National Park, in our data
West Coast National Park is the only park on Wallace's Line with enough records to rate Sand-Dune Widow sightings: about 10% of wildlife watchers there report one on a given day.
Same family: Nymphalidae
The closest relatives of the Sand-Dune Widow that you can see in West Coast National Park (family Nymphalidae, Brush-footed Butterflies) are Silver-Bottom Brown (about 20%) and Painted Lady (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Sand-Dune Widow is recorded against all the insects logged in West Coast National Park (5 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.
