Bug FAQEarly Thorn
Selenia dentaria · Order: Lepidoptera · Family: Geometridae
The Early Thorn moth has a wingspan of about 28 to 40 mm and shows highly variable colours with scalloped wings and three crosslines on the forewings, plus a dark spot at the wing tip. It lives across northern Europe and the Palearctic region extending to the Caucasus, Siberia, the Russian Far East, Amur and Mongolia, and its larvae feed on birch and alder trees. Adults fly in two generations from April through August.
Source: Wikipedia
How to recognize it
The forewings have three crosslines, a dark stain at the apex, and the wings are scalloped. Colouration is extremely variable, with less deep hindwing excision, enlarged costal spots, and poorly developed transparent discal marks.
Source: Wikipedia
Size
Wingspan ranges from 28 to 40 mm.
Source: Wikipedia
Life cycle
The moth produces two generations of adults that fly from April to August.
Source: Wikipedia
When you see it
Adults are on the wing from April through August in two broods.
Source: Wikipedia
Where it comes from
Its native range covers northern Europe and the Palearctic region extending eastward to Mongolia.
Source: Wikipedia
Lookalikes
The summer generation ab. illunaria is smaller and less speckled, while the dwarf form ab. minima is sharply marked and common in Arctic Norway.
Source: Wikipedia
More photos
Questions people ask
When can I see Early Thorn moths?
Adults fly in two generations from April to August.
Source: Wikipedia
What does the Early Thorn look like?
It has scalloped wings with three crosslines, a dark spot at the forewing tip, and highly variable colouration.
Source: Wikipedia
Same family (Geometridae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Selenia_dentaria
Look it up elsewhere: GBIF · iNaturalist · BugGuide · Wikipedia
Text written 2026-10-24 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.