Curetis acuta
In 3 days ~30% in a week ~50%
Curetis acuta, the angled sunbeam, is a species of butterfly belonging to the lycaenid family. It is found in Indomalayan realm. Curetis acuta is sexually dimorphic, the sexes differing in dorsal coloration of the wings, however their ventral wings are similar and of silver color which reflects sunlight. The reflection of light by silver ventral wings plays a role of signalling during flight, camouflage while at rest or during hibernation, and lowering body temperatures by reflecting the sunlight.
Forewing with broad black margins, broadest at the apex and at the hinder angle; the inner border of the black margin almost evenly rounded, the black marginal band running inwards also on the hinder margin, narrowing rapidly basally and terminating about the middle; a black spot at the end of the cell running into the costal black band; some greenish-brown irrorations at the base of the wing; apex very acute, the outer margin being somewhat concave below it, hinder angle triangular, hinder margin nearly as long as the costa, the outer margin consequently erect, though slightly sinuous. Hindwing with greenish-brown irrorations at the base and broadly on the abdominal area... Wikipedia →
| # | Park | Country | Daily sighting probability |
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More parks will be added in future updates.
With luck
About 10% of wildlife watchers report an Angled Sunbeam sighting in Tokyo on a given day, based on 262 verified sightings from GBIF citizen-science data. It is the 63rd most-seen of the 1013 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.
September to November
In those months about 20% of wildlife watchers report an Angled Sunbeam in Tokyo on a given day, against under 5% in January–February and April–June, the lowest months.
Between 8 and 11 am
Across all the parks we cover, that three-hour window holds the most Angled Sunbeam sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
6th of 11
Of the 11 cities where we can rate Angled Sunbeam sightings, Tokyo ranks 6th at about 10%. The best odds are in Nanjing (China, about 20%), Nagoya (Japan, about 10%) and Sendai (Japan, about 10%).
Same family: Lycaenidae
The closest relatives of the Angled Sunbeam that you can see in Tokyo (family Lycaenidae, Gossamer-winged Butterflies) are Pale Grass Blue (about 30%), Small Copper (about 20%) and Pea Blue (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Angled Sunbeam is recorded against all the insects logged in Tokyo (262 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.
