Papilio prexaspes
In 3 days ~20% in a week ~40%
Papilio prexaspes, the blue Helen, is a swallowtail butterfly found in Southeast Asia. The race found in the Andaman and Nicobar Islands, Papilio prexaspes andamanicus (earlier placed under Papilio fuscus), is also known as the Andaman Helen.
The taxonomic description below is of race prexaspes and is taken from Charles Thomas Bingham's 1907 book (in the public domain): Closely resembles Papilio chaon, from which it differs as follows: smaller; fore wing more produced, its termen concave.
Male has the ground colour of the upperside of the wings a more brownish sooty-black. Hind wing with the upper discal white patch extended into interspace 4, most usually very slightly so, often represented only by a very small spot of white scaling, a white spot also above the tornal angle. Underside, fore wing: the internervular brownish-yellow streaks limited to the apical area of the wing. Hind wing: the upper discal patch extended to the dorsum in a series of three pure white not ochraceous-tinted spots, a more or less incomplete postdiscal series of lunules formed of diffuse blue scales, and the subterminal series of ochraceous lunules of a darker colour and smaller than... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Kaeng Krachan National Park | 🇹🇭 Thailand |
More parks will be added in future updates.
With luck
About 10% of wildlife watchers report a Blue Helen Swallowtail sighting in Kaeng Krachan National Park on a given day, based on 9 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 194th most-seen of the 296 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
February to June
In those months about 10% of wildlife watchers report a Blue Helen Swallowtail in Kaeng Krachan National Park on a given day, against under 5% in July to January, the lowest months.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Blue Helen Swallowtail sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Only Kaeng Krachan National Park, in our data
Kaeng Krachan National Park is the only park on Wallace's Line with enough records to rate Blue Helen Swallowtail sightings: about 10% of wildlife watchers there report one on a given day.
Same genus: Papilio
The closest relatives of the Blue Helen Swallowtail that you can see in Kaeng Krachan National Park (genus Papilio, Common Swallowtails) are Great Mormon Swallowtail (about 30%), Paris Peacock Swallowtail (about 20%) and Common Mormon Swallowtail (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Blue Helen Swallowtail is recorded against all the insects logged in Kaeng Krachan National Park (9 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.
