Hydrometra stagnorum
In 3 days ~20% in a week ~50%
Hydrometra stagnorum, the common water-measurer, is a species of aquatic bugs in the family Hydrometridae, the water measurers. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cévennes National Park | 🇫🇷 France | |
| 2 | Sierra Nevada National Park | 🇪🇸 Spain | |
| 3 | Pyrénées National Park | 🇫🇷 France | |
| 4 | Wadden Sea National Park | 🇩🇪 Germany |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Paris | 🇫🇷 France | |
| 2 | Porto | 🇵🇹 Portugal | |
| 3 | Berlin | 🇩🇪 Germany | |
| 4 | Hamburg | 🇩🇪 Germany | |
| 5 | Munich | 🇩🇪 Germany | |
| 6 | London | 🇬🇧 United Kingdom | |
| 7 | Essen | 🇩🇪 Germany | |
| 8 | Birmingham | 🇬🇧 United Kingdom | |
| 9 | Warsaw | 🇵🇱 Poland | |
| 10 | Copenhagen | 🇩🇰 Denmark |
With luck
About 10% of wildlife watchers report a Common Water Measurer sighting in Sierra Nevada National Park on a given day, based on 7 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 390th most-seen of the 479 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 50%, if each day is a fresh chance.
March
In that month about 30% of wildlife watchers report a Common Water Measurer in Sierra Nevada National Park on a given day, against under 5% in April–June, August and October–February, the lowest months. That is one of Sierra Nevada National Park's wettest months, with about 130 mm of rain against 30 mm in July.
Between 2 and 5 pm
Across all the parks we cover, that three-hour window holds the most Common Water Measurer sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Among the best
Of the 4 parks where we can rate Common Water Measurer sightings, Sierra Nevada National Park ranks 2nd at about 10%, level with the leaders once rounded. The best odds are in Cévennes National Park (France, about 10%).
Same order: Hemiptera
The closest relatives of the Common Water Measurer that you can see in Sierra Nevada National Park (order Hemiptera, True Bugs, Hoppers, Aphids, and allies) are Red Shield Bug (about 30%), Sloe Bug (about 30%) and European Striped Shield Bug (about 30%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Common Water Measurer is recorded against all the insects logged in Sierra Nevada National Park (7 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.
