Hydriomena impluviata
In 3 days ~10% in a week ~30%
The May highflyer (Hydriomena impluviata) is a moth of the family Geometridae. It is found across the Palearctic region and the Near East although its range is largely determined by the presence of its larval food plant. The species was first described by Michael Denis and Ignaz Schiffermüller in 1775.
The wingspan is 30–34 mm and it is quite variable in markings, the best identification feature being four square spots along the costa of each forewing, although these may not be visible in the frequent melanic forms. "Individual specimens of coerulata (synonym of impluviata) bear a very close resemblance to Hydriomena ruberata. coerulata (impluviata) is perhaps on an average slightly smaller, is somewhat shorter-winged, oftener with a very pale, blue-green median band, the oblique subbasal line is straight, or only very weakly angulated in the cell, the black marks on the hindmargin of the forewing and on the anterior veins distally, which generally characterize both species, on an average less strongly developed than in ruberata but very variable in both species".
The larva is relatively powerful and dark red-purple in colour. It has some short setae. The species flies at night from May to July [1] and is attracted to light. The larva feeds on the leaves of alder, spinning two leaves together so it can feed undisturbed. The species overwinters as a pupa under loose alder bark.
^The flight season refers to the British Isles. This may vary in other parts of the range. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Wadden Sea National Park | 🇩🇪 Germany |
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Liverpool | 🇬🇧 United Kingdom | |
| 2 | Birmingham | 🇬🇧 United Kingdom |
Rare
Under 5% of wildlife watchers report a May Highflyer sighting in Birmingham on a given day, based on 12 verified sightings from GBIF citizen-science data. It is the 470th most-seen of the 811 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 30%, if each day is a fresh chance.
May and June
In those months about 10% of wildlife watchers report a May Highflyer in Birmingham on a given day, against under 5% in July to April, the lowest months.
Between 6 and 9 am
Across all the parks we cover, that three-hour window holds the most May Highflyer sightings with a recorded time, and about 7 in 10 of them come between 6 am and 6 pm: it is most active around dawn and dusk.
2nd of 2
Of the 2 cities where we can rate May Highflyer sightings, Birmingham ranks 2nd at under 5%. The best odds are in Liverpool (United Kingdom, about 10%).
GBIF citizen-science records
It is estimated from how often the May Highflyer is recorded against all the insects logged in Birmingham (12 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.
