Pachycnemia hippocastanaria
In 3 days ~20% in a week ~40%
Pachycnemia hippocastanaria, the horse chestnut moth, is a moth of the family Geometridae. It is found in most of Europe. The wingspan is 28–32 mm. Adults are on wing from April to May, and again in a partial second generation in August, usually with fewer and smaller moths. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cévennes National Park | 🇫🇷 France | |
| 2 | Wadden Sea National Park | 🇩🇪 Germany | |
| 3 | Sierra de Guadarrama National Park | 🇪🇸 Spain | |
| 4 | Pyrénées National Park | 🇫🇷 France |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Porto | 🇵🇹 Portugal |
With luck
About 10% of wildlife watchers report a Horse Chestnut Moth sighting in Porto on a given day, based on 49 verified sightings from GBIF citizen-science data. It is the 134th most-seen of the 498 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.
August
In that month about 20% of wildlife watchers report a Horse Chestnut Moth in Porto on a given day, against under 5% in March–April, June–July and December, the lowest months. That is one of Porto's driest months, with about 20 mm of rain against 140 mm in January.
Between 11 pm and 2 am
Across all the parks we cover, that three-hour window holds the most Horse Chestnut Moth sightings with a recorded time, and about 7 in 10 of them come between 6 pm and 6 am: it is seen both by day and at night.
Only Porto, in our data
Porto is the only city on Wallace's Line with enough records to rate Horse Chestnut Moth sightings: about 10% of wildlife watchers there report one on a given day.
Same family: Geometridae
The closest relatives of the Horse Chestnut Moth that you can see in Porto (family Geometridae, Geometer Moths) are Double-Striped Pug (about 20%), Vestal (about 20%) and Pale Oak Beauty (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Horse Chestnut Moth is recorded against all the insects logged in Porto (49 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.
