Bug FAQScallop shell moth
Rheumaptera undulata · Order: Lepidoptera · Family: Geometridae
Also called: Scallop Shell
The scallop shell moth has a wingspan of about 25 to 30 mm and pale forewings with many wavy dark crosslines and a scalloped fringe on the outer edge. It lives in light quarry and flood-plain forests, bushy forest edges, gardens and parks, and can be found up to 1500 m in the Alps. Its larvae feed on a variety of trees and shrubs such as birch, willow, aspen and several berry plants.
Source: Wikipedia
How to recognize it
The forewings are pale with numerous wavy dark crosslines and a pale brown outer margin that has a scalloped fringe; the hindwings are similar but paler.
Source: Wikipedia
Size
The adult’s wingspan ranges from 25 to 30 mm.
Source: Wikipedia
Where it lives
In the Alps it can be found at elevations up to about 1500 m.
Source: Wikipedia
What it eats
Caterpillars feed on birch species, various Vaccinium plants, willow species, aspen, poplars, barberry, alpine currant, spirea, rowan, sea buckthorn and bog myrtle.
Source: Wikipedia
Life cycle
There is one generation each year; adults fly from late May through August in Europe. The species overwinters in the pupal stage.
Source: Wikipedia
Where it comes from
It occurs across most of the Palearctic region and in North America.
Source: Wikipedia
Where it is found in the US
Recorded in 30 of 51 states and DC. Most records: Alaska, Oregon, Colorado, Washington, New Hampshire, New Jersey, Massachusetts, Pennsylvania.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in Canada. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
What does the scallop shell moth look like?
It has a pale ground colour on the forewings with many wavy dark crosslines, a scalloped pale-brown fringe on the outer margin, and paler hindwings; the wingspan is 25 to 30 mm.
Source: Wikipedia
When can I see adult scallop shell moths?
Adults are active from the end of May through August.
Source: Wikipedia
What plants do the larvae feed on?
The caterpillars eat leaves of birch, willow, aspen, poplars, various Vaccinium species, barberry, alpine currant, spirea, rowan, sea buckthorn and bog myrtle.
Source: Wikipedia
Same family (Geometridae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Rheumaptera_undulata
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-25 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-25.