Thoressa varia
In 3 days ~40% in a week ~70%
Thoressa varia is a butterfly of the family Hesperiidae. It is found on the islands of eastern Asia, including the Sakhalin Islands and Kuril Islands, Japan, the Korean Peninsula and north-eastern China. Its Japanese common name kochabane-seseri can be translated as "small brown wing" (ko means "small" and chabane means "brown wings").
The length of the forewings is 16–18 mm. Adults are on wing each year from June to July. There are one to two generations per year. The larvae feed on Sasa kurilensis. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Nikko National Park | 🇯🇵 Japan |
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Tokyo | 🇯🇵 Japan |
Possible
About 20% of wildlife watchers report a Japanese Swift sighting in Nikko National Park on a given day, based on 5 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 53rd most-seen of the 86 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.
July
In that month about 40% of wildlife watchers report a Japanese Swift in Nikko National Park on a given day, against under 5% in February–June and September–December, the lowest months. That is one of Nikko National Park's wettest months, with about 240 mm of rain against 100 mm in November.
Between 2 and 5 pm
Across all the parks we cover, that three-hour window holds the most Japanese Swift sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
Only Nikko National Park, in our data
Nikko National Park is the only park on Wallace's Line with enough records to rate Japanese Swift sightings: about 20% of wildlife watchers there report one on a given day.
GBIF citizen-science records
It is estimated from how often the Japanese Swift is recorded against all the insects logged in Nikko 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.
