Eurema andersoni
In 3 days ~30% in a week ~60%
Eurema andersonii, the one-spot grass yellow or Anderson's grass yellow, is a small butterfly of the family Pieridae, that is, the yellows and whites, which is found in Bangladesh, India, Myanmar and other parts of Asia.
Wet form: Male. Upper-side. Fore-wing with the outer marginal band moderately broad, the medial portion inclined slightly inward, and the lower portion very slightly inclined obliquely-outward. Hind-wing with a moderately broad outer band. Underside with slightly defined ordinary markings. Fore-wing with two cell-marks, basal obsolescent. Female not seen.
Dry form (fig. 2a, b). Male. Upper-side similar to the wet form. Underside with the ordinary markings distinct. Fore-wing with a medial cell mark, and a more or less well-defined sub-apical patch. Female. Upper-side paler. Fore-wing with slightly broader outer band. Hind-wing with a moderately broad outer band. Underside similar to the male. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cat Tien National Park | 🇻🇳 Vietnam | |
| 2 | Taroko National Park | 🇹🇼 Taiwan | |
| 3 | Kaeng Krachan National Park | 🇹🇭 Thailand |
With luck
About 10% of wildlife watchers report a One-Spot Grass Yellow sighting in Cat Tien National Park on a given day, based on 8 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 96th most-seen of the 125 insects we can rate there. Over three days the chance rises to about 30%, and over a week to about 60%, if each day is a fresh chance.
February
In that month about 30% of wildlife watchers report a One-Spot Grass Yellow in Cat Tien National Park on a given day, against under 5% in January, March, May and July–October, the lowest months. That is one of Cat Tien National Park's driest months, with about 15 mm of rain against 490 mm in July.
Between 8 and 11 am
Across all the parks we cover, that three-hour window holds the most One-Spot Grass Yellow sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Yes
Of the 3 parks where we can rate One-Spot Grass Yellow sightings, Cat Tien National Park has the highest daily chance: about 10%. Next come Taroko National Park (Taiwan, about 10%) and Kaeng Krachan National Park (Thailand, about 10%).
GBIF citizen-science records
It is estimated from how often the One-Spot Grass Yellow is recorded against all the insects logged in Cat Tien National Park (8 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.
