Idaea contiguaria
In 3 days ~10% in a week ~20%
Idaea contiguaria, the Weaver's wave, is a moth of the family Geometridae. It was first described by Jacob Hübner in 1799 and is found in Europe. The species has a wingspan of about 20 mm.South describes it- "In colour, the moth is whity brown, more or less dusted or clouded with dark grey; except in the darker forms, three irregular black lines on the fore wings, and two on the hind wings, are clearly seen. It flies at dusk in June and July and sits by day on lichen-covered rocks. The caterpillar is pale ochreous brown, with irregular dark brown lines. It feeds on ling (Calluna) and crowberry (Empetrum) from September to May; but when eggs are obtained, the caterpillar hatching from them may be kept on chickweed, knotgrass, etc., and the moth be reared the same year. Mr R. Tait records the finding of ten caterpillars on navelwort (Cotyledon) growing among the heather in a very sheltered corner among rocks in North Wales, at Easter, 1906. He also notes that moths reared in captivity pair readily. The British localities, all in North Wales, are Aber, Bangor, Barmouth, Bettws-y-coed, Conway, Dolgelly, Llanfairfechan, and Penmaenmawr."
The adults fly in one generation from June to July [1]. The larvae feed on heather, crowberry and Umbilicus. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cévennes National Park | 🇫🇷 France | |
| 2 | Pyrénées National Park | 🇫🇷 France | |
| 3 | Sierra de Guadarrama National Park | 🇪🇸 Spain |
Rare
Under 5% of wildlife watchers report a Weaver's Wave sighting in Sierra de Guadarrama National Park on a given day, based on 6 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 473rd most-seen of the 597 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
August and September
In those months about 10% of wildlife watchers report a Weaver's Wave in Sierra de Guadarrama National Park on a given day, against under 5% in October to July, the lowest months. Those are among Sierra de Guadarrama National Park's driest months, with about 35 mm of rain a month against 110 mm in November.
Between 9 pm and midnight
Across all the parks we cover, that three-hour window holds the most Weaver's Wave sightings with a recorded time, and about 8 in 10 of them come between 6 pm and 6 am: it is mostly seen at night.
3rd of 3
Of the 3 parks where we can rate Weaver's Wave sightings, Sierra de Guadarrama National Park ranks 3rd at under 5%. The best odds are in Cévennes National Park (France, about 10%) and Pyrénées National Park (France, under 5%).
Same genus: Idaea
The closest relatives of the Weaver's Wave that you can see in Sierra de Guadarrama National Park (genus Idaea) are Portland Ribbon Wave (about 10%), Idaea ostrinaria (about 10%) and Bright Wave (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Weaver's Wave is recorded against all the insects logged in Sierra de Guadarrama National Park (6 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.
